They already did! The 'presidential immunity' ruling they recently made basically said that if a President does it, we (SCOTUS) will decide if it is an official act, and if it is, then the Prez is blameless, but if we say the act isn't 'official' then WE will tell you the Prez is a baddie.
Fascists rely on you being a decent person in indecent times. They're counting on Biden not using the full extent of the powers the office of the President has been granted because it's so far beyond the pale.