Reading between the lines, which risks being completely wrong, I wonder if you mean dungeons? The first is at level 15 and story takes you through 4 by the time you reach level 20 storyline. Of course if you don't do the story quests you won't get them. (story quests looks like flames around the icon )
Fates start low level, guild hests and guild leves at level 10. The option to take any other class as well as your starter class opens at level 10 of your class quests. Travel at level 15 unlocked by story quests allows you to visit the other cities/areas.
As for the new content they only added this week tbh I don't know what levels they start at but you only have to read the patch notes to find that out. With more dungeons, PVP, treasure maps and so much more.