Kingston is the first area you'll fight in The First Descendant after completing the tutorial. Despite its small size, the developers have put a large portion of it behind the game's progression system.
How to Unlock Grand Square in Kingston (Easy Guide)
The largest section is the Grand Square, which is walled off until players meet certain criteria to unlock it. If you try to go there early, you’ll be told you can’t enter until you become a better player, which is a rude way of telling you that you’re going the wrong way.
The Grand Square area in Kingston in The First Descendant is locked off after the main story, so you'll need to complete the main missions first to unlock it.
After you beat the Magistar Lair raid by yourself, with friends, or with random players and get the Bunny Spiral Catalyst in the process, the Grand Plaza should open up as part of the story. Here you can access the area, the quests, and the secondary raid behind it.