report this person i guess
omg i see someone cheating what do i do

Nothing you can do. Report them to your heart's content, as much as you like. No one cares and nothing will ever be done about it. It's too lucrative to sit on your hands and do zero.

Yes report the player if you can see the username.
https://support.chess.com/article/209-how-do-i-report-someone
That said, discussions of cheating, potential cheating, or cheat detection are not allowed in the general forums.
title! help! hes sitting right next to me! hes cheating! with stockfish! help!