There’s a ton of information in game…and a ton of information online.
Literally. Written, videos, you name it.

I agree that the game can be overwhelming for a beginner as it seems to have too much going on but literally anything you need to find out is in a blue quest marker or one google search away. Most games do that, you have one icon for side quests, one marker for the “main” or quests you can learn something from.

Once you finish the duty required for the story you get a text telling you now you can speak with whoever to unlock the extreme version, you do that and then you have a few options, you queue through duty finder or you go at party finder, join a practice group and have a bit of consideration for other people to watch a guide before, say you are new, most likely they are as well and don’t expect you to be perfect, it is a practice group after all and if you don’t want to do that and you want a blind run you make your own group and you will figure each mechanic by dying and getting back up, or you join someone else’s group that states it is a blind run, if nothing is written you can always ask the party leader.

And for those saying “but how can a sprout know a party finder even exists?????” well, the game tells you, and if you didn’t notice that, don’t you go through the menu on any new game you begin playing? If you don’t then you really should that’s the most basic thing you can do to help yourself. Set aside twenty minutes and go through all the settings when you begin any game, almost everything is explained throughly and as I said, if you need further explanations there are a ton of guides online, and the majority of the written guides are spoiler free for the rest of the game except that one thing you are searching for.