You'd have to overthrow parts of the US government to keep power for a 3rd term I'd still call that a coup even if it's coming from inside the house. Coups rarely come from entirely external forces, the military basically always has a major role in deciding if a coup is successful even if it's just staying neutral and seeing where the chips fall.
Trump has already "overthrown" the executive on every major part of the US government using executive, judicial and legislative processes. Sometimes this has been illegal (ex FCC). Nobody calls it a coup.
