“Narrow Precedent”. I don’t see it happening because they have no loyalty to Trump, but it could.
They can vaguely rule that some unique aspects of the Trump case makes it different unique and that courts should not take it as jurisprudence for future cases. There’s more to it, obviously. Lower courts can “narrow” a SCOTUS precedent if it is defensible to do so by being able to defend their interpretation as non-contradictory to the SCOTUS precent (some subtle differences from the case law), but SCOTUS occasionally instructs that a decision should not be taken as precedent. Lower courts can ignore that (and afair, it has happened), but it leaves SCOTUS open to the idea of Biden being prosecuted in the future.