The studio wants to move away from Dungeons & Dragons entirely.
A lizard person mage.

During a Game Developers Conference (GDC) panel, Larian Studios founder Swen Vincke revealed that the studio has no plans to release any expansions or DLC for Baldur's Gate 3. Furthermore, the studio may never work on a Baldur's Gate 4 at all. This is according to information shared from the GDC panel via IGN.

Vincke said during the panel that Larian wants to move away from Dungeons & Dragons entirely. He said that the studio would like to do something new and will instead leave the IP with Wizards of the Coast. Obviously, it's a little too early to say whether or not Hasbro, which owns Wizards of the Coast, will seek another developer for a possible Baldur's Gate 4.

The possibility of Baldur's Gate 3 DLC or expansions was tossed around for a little while at Larian, but these new statements seem to have put those thoughts to bed for good.

Baldur's Gate 3 continues to be a massive success for all studios involved. The game won even more Game of the Year awards this week at the Game Developers Choice Awards. In addition to winning Game of the Year, Baldur's Gate 3 also won for Best Narrative, Best Design, and the Audience Award.