It is. [ Trying to figure out the mechanics of this place is going to become a fixation for him, probably, because it's a good place to put mental energy that might otherwise get stuck on things like "the fate of everyone he knows and loves" or "another near-death moment." ] A domain is...think of it as a way for a sorcerer to take control of a small area. Flood it with so much of their power that they can define the terrain and what happens to anyone caught in it.

[ It's a bit oversimplified, probably, but he's yet to encounter another jujutsu sorcerer here, so there's no point in getting stuck on technicalities. ]

It's one of the crowning techniques of jujutsu sorcery. Most can't pull it off, and even those who can do so under strict limitations. The size of that one, though--it's ridiculous.

[ So while he doesn't expect that whatever runs this place is operating on the same set of rules he's learned, it's nonetheless chucking around a level of power that he presumes is at the very least on par with Ryomen Sukuna...which is a pretty terrifying thought.

We might all be pretty fucked, to be succinct. ]