Confused at endgame! Help

Greetings
New player here, aprox. a month old. Roegadyn warrior.
I've finished the MSQ until 5.3 Reflections in crystal. I have neo-ishgardian set (480).
However, I'm feeling totally lost. After a quick google and youtube search, I ended more confused, every guide describes different patches. What should I do at endgame? I heard about a relic weapon but I have 0 idea what is that. My past MMORPGS were WoW and ESO for the record. If I can get some advices, a quick guide, or anything to point me in the right direction, thank you!

There are different things that you can do to pass time after story.
You can:
1) unlock the normal raids . then if you want some content with a bit more meat go do savage after you do the normals. there are also ultimate fights for an even meatier challenge if you go through with savage
2) you can unlock extreme version of trials you did prior , they are a decent start
3) you can level other jobs from the very start though it isnt what id call an endgame
4) you can try your hands on crafting and/or gathering , its a game in off itself along with trying to get as much gil as possible. if gil is not your fancy you still get benefits from it, such as being able to self repair whenever you want, as well as being self sufficient on gear, food and pots
5)You can try your hand for bosja , i dont remember where the quest starts but by going for it you also unlock the relic quests. Relic is a weapon that is only outshined by the current raid weapon. In bosja you will find imo the best content in the game, a 48man with exclusive actions to use and a focus on Co operation between the parties that you have to make from scratch.
6) Glamour

There's multiple major things to do after MSQ is completed, but in terms of combat the main ones are
1.Normal/Savage Raids. Specifically the Eden raid series for this expansion. 3 tiers of 4 bosses spread out over the course of the expansion. The final tier will drop with the next major patch. Savage raiding is considered the "true" endgame for hardcore players, it's the most difficult content in the game (aside from Ultimate tier, but that's basically bonus). Normal difficulty is where the story is at though, so anyone should be able to experience that. Savage is largely for the challenge, Best in slot gear, and dyable versions of the normal tier armor.

2.Alliance raids, specifically the Nier raids this expansion. 28 person raids, pretty self explanatory. When current, the gear they drop serves as catch up gear (not quite as strong as current Best in Slot gear, but only about 5 ilvls off) and you also get coins which can be used to augment the tomestone gear (which otherwise can only be upgraded with savage).

3. Trials. Each major patch aside from .1 has a new trial. The .3 patch's trial is connected to MSQ, but the other trials are part of an optional storyline, with this expansion being the Weapon robots from FF7 (so far Ruby weapon and sorta Sapphire weapon in a solo fight). Normal difficulty is part of the story, extreme difficulty is 100% optional. Extreme is a middleground between normal difficulty fights and Savage. It requires fight knowledge, teamwork, and proper understanding of your class for a certain level of DPS, but it is not nearly as deadly or intensive.

4. The relic weapon. Every expansion has a relic weapon that you work on over the course of the expansion. This expansion is a bit different in that there's a prerequisite to even start the series. You need to do the Stormblood alliance raids (Return to Ivalice) first to unlock the relic weapon. Relic Weapons are generally largely about the glamour, they become Best in Slot at the end of the expansion, but before then they tend to fall into the "catch up gear" territory. Relic weapons tend to be something of a grind to get, but they rarely require much active skill, just patience.

Aside from that, there's crafting and gathering. Each crafter and gatherer class acts like combat classes in that they start at level 1 and have to be leveled to 80 and have their own tools and gear with stats that you upgrade as you progress.

There's also beast tribes. Each expansion has 3 beast tribes (ARR has 5 instead, but they take less time to individually complete) that serve as daily quests. Maxing out each beast tribe in an expansion unlocks a questline that gets you extra goodies (on top of the mounts, minions, emotes, etc that each beast tribe gives individually), but you'll need a crafter and gatherer leveled on top of a combat class to access them all (in HW you just needed a crafter for one tribe, in SB you could use either a crafter or gatherer for one tribe, in ShB there's a tribe for combat, crafters, and gatherers each instead of 2 combat tribes and one tribe that was crafting or crafting and gathering.) It takes roughly a month to max out any given tribe, and you can be working on two to 3 per day (the numbers are a bit different with ARR due to how they work).

Short version, for current content look into the Eden Raids, the Nier Alliance Raids, Bozja (for the relic weapon, first do the Return to Ivalice Alliance raids), and the Sorrows of Werlyt for the Trials.
The Eden Raid's final tier will be out in December (likely) with 5.4, the final Nier raid tier will be out like 3-4 months after that, Bozja will likely get another phase in 5.4, and Sorrows of Werlyt will get a new fight in both 5.4 and 5.5. (And the combined beast tribe quest will likely be in 5.55, the final final main patch before 6.0).

What should you do? Whatever it is that you like in the game. A set of Neo-ishgardian gear will be enough to get you through the story content of the next patch(dec). You would be slightly behind the "average" player, but no where near enough to hinder your ability to do the story. If you want upgrades now you have a few options. You can buy an item in Kholusia that will add 10 levels to your crafted gear(you lose the ability to overmeld in the exchange). You can also spend allegory tomes(these have a weekly cap, so if this is something that interests you try to cap each week until the patch) for pieces at that same 490 level. The current alliance raid will also drop a different set of 490 gear(these have a 1 piece per week limit right now - visible armor slots only), along with a token you can use to upgrade some of those allegory pieces to level 500. And if you like more challenging encounters, the current extreme trial(seat of sacrifice) will drop a weapon upgrade for you and you can try to get into the savage raids which have a full set of gear for the taking. Mind you, when the next patch hits a new tier of gear will be released(gear upgrades come every even numbered patch, and this next one is 5.4). You could potentially just wait 4-6 weeks, then start getting the level 510-530 gear that the rest of us will also be working on. This will be new tome gear(with new tomes), new crafted gear, new extreme trial weapons, new raid gear, and new savage raid gear.

Aside from gear, you could work on side story quests. The eden and nier raid lines both have story associated with them, as does the optional trial storyline(the weapons). Eden and the trials being continued in the next patch(nier is the following patch) means catching them up now will give you more to do right away next patchday. As was mentioned previously, the relic is tied to the Bozja story that you could get into. The previous expansions also had optional raids and trials, each with their own storyline(none of these are relevant gear wise, but you can find glamours minis mounts and music you may want) - and each one also had their own version of a relic quest(awesome glamours, kinda grindy). If you want a change of pace from combat, you could get involved in rebuilding Ishgard via crafting and gathering(we're rebuilding the Firmament section of the city via the ishgardian restoration quests and content). The beast tribes would fall into this "change of pace" by my estimation(even the combat tribes dont need much fighting from you), and again each has a story to tell. The Hildibrand and Postmoogle side quests are more comedy oriented if you could use a couple laughs after some downer storylines. You could get an apartment to decorate(or try for a house, though i can say from personal experience Lamia isnt the best server to try to find a house on). You can spend time in the Gold Saucer racing chocobos and playing cards(they have some nice glamours/mounts/etc you can save up for). You can dip a toe into PvP(not this games strong suit, but some enjoy it). You can level other classes. You can obsess over fashion. Or work on your mount/minion/music collections. Or recruit the perfect squadron. Or try to get all the rewards from the current limited time events(yokai and make it rain) before they end. Or challenge yourself to complete Palace of the Dead/Heaven on High solo. Or unlock all the optional dungeons you might have skipped and run each of them once to see what they have to offer. Or try to get into a good static group(in general FF14 savage raids are completable in a PuG setting, but a fixed group tends to make them much easier as you can develop your own strategies and learn to work with each other) to prog the next savage raid tier with.

Ultimately, there are a lot of paths open to you but only you know which ones you would enjoy walking.