Create: duplicates + precomposes the selection (original stays visible); keyframe the [CAMERA] inside — the master stays lined up. Add Track Mask → position & track it → Stabilized Precomp for a punch-in held still, motion re-applied live. Precomp size is a share of the source comp: on Create the picture scales down with the frame and the master comp is unchanged; on Stabilized it is a floor under the punch-in, which still grows if the mask needs more room. Punch-in scale is the other axis: same framing, more pixels — a small crop that came back too small to work in is what ×2 to ×4 is for.