You can go in and manually turn on “Capture the King” in settings to play this way.
Allowing king's suicidal moves in 4pc

there is a version of four player chess called "4pc max" (with capture the king enabled). You can even play rated games.
there is a version of four player chess called "4pc max" (with capture the king enabled). You can even play rated games.
like in Chaturaji, may make things more interesting, or at least different in a not uninteresting way.
Ex, if a king can be allowed to move right next to an enemy queen, because it's 4pc and the other two players can still make moves that prevent your opponent from eating your king and so your king can possibly eat an enemy queen. King then can be a more active piece. But I suppose there was some good reason not to do that in 4pc chess though I don't know what exactly.