I think Larian said at some point that they have no current plans to work on a DM mode for BG3 (maybe just not during EA..?), which seems like it'd be a prerequisite for such a game mode.
Unless you're talking about some sort of system that randomly generates content/encounters/areas--i.e, random dungeons (in the broadest sense of the term)--which would also take a bunch of work and is more like a standalone game or a full ~$30+ DLC addition. Getting into the MMO territory too..
I'd be a fan of either.
