Actors ask “What’s my frame” or “What’s my framing?” because they want to know how much room they have to move in the film frame. The answer to the question is “Why would you want to move?” You’re not going to move any more in the wide shot than you are in the medium shot or else the shots won’t cut together.
If you have to move on camera, move back and forth and not side to side. Side to side movement makes an actor look less experienced because side to side movement is harder to edit. Back and forth movement is better because back and forth movement syncs up with the film frames which come out of the camera and toward the actor as if on a conveyor belt. The actor’s job is to thread his or her moments through those frames. This is how an actor develops a working relationship with the film camera.
If you want to look like a natural on camera, don’t play naturalism. Naturalism in the film frame comes across as messy and hard to edit, and it takes the tension out of the scene and out of the frame. Tension in the film frame is what commands the attention of the film camera. The job of the actor when stepping into the film frame is to harness energy and focus it. Releasing energy and tension results in the camera losing interest. On camera, if you want to come across naturalistically, you need to be play the scene cinematically.
If you only follow one rule, follow this one. You can move in the film frame all you want as long as you move as the character . However, if you’re creating character and not just playing a scene, you’ll end up not moving very much anyway.