https://docs.larian.game/Command_listGo to divinity engine 2 directory and find ReCon. You can use commands from the link above with it. It seems to have an AddDungeonMaster Command, so perhaps you can simply add that onto your solo game and go ham. I wish I could tell you if it works or not, but I can't get ReCon to connect

edit: My bad, this only works for the editor. Doesn't work in SP.