My child keeps taking away the toy a sibling is using. How can I teach "can I have it" and "wait"?

In the moment, stop the tug-of-war and briefly put the situation into words: "You wanted to use it. Right now it's ○○'s turn." Help return the toy, and make the point of switching visible using something like a sand timer or "when this song ends." While they wait, have a similar toy or a different role ready. During calm play, practice just one of the following for "can I have it"—words, a gesture, or a card—and acknowledge the moment they actually use it.