How do devs of games with big worlds (BotW, Skyrim, etc) work on the map? Do they "check out" chunks of it and only work on one at a time? Or does their editor have a way to merge nicely when people work on different areas at the same time?

How does an undo stack work if the map editor loads in other designers changes while you're working.... it seems complicated lol

the easiest method by far seems to be splitting the world into big "chunks" and then one person can only work on one chunk at a time. Then it's just like any other source control file.

(I know for game loading reasons it's already split up like that. I'm more thinking about the editor, where designers would want to be able to seamlessly edit the world but also conflicts / undo's need to still resolve nicely as other people edit other parts).