"If you get in the bath, I'll go and choose a bath toy that you've never even played with before." (And then I find something random in the kitchen - ladle, colander, Tupperware, etc.)
or "If you get dressed, I'll tell you something interesting about Mercury." (Or owls, or bullet trains or anything you can come up with.)
Used the Mercury one with my 4yo, planning to tell him about the massive valley recently discovered. He shot back immediately "Dad, I already know it's really hot on one side and cold on the other side!"
If they're out of control and won't listen to reason, I often just talk somewhat quietly to them about something I know they'll find interesting, and they usually stop screaming so they can hear what it is.