I know the main reason this command was possible in those games was due to the nature of hot-seat being pre-programmed into those games (which was it's own levels of fun that I miss). I know with how much the engine of total war has changed since then, but if that's possible, even if another mod all together it would be really cool.
I like playing vanilla but sometimes I just like goofing around on a save like you can in a lot of Paradox games.