Law is unsettled on that. Theoretically he could pardon himself on any Federal Cases but not any of the state cases. No president has ever been stupid enough to try that. His popularity would take a huge hit, and as we've seen before the House would just impeach him for something and this time the Senate would convict him and boot him out. That's likely why Biden hasn't tried to pardon any of his family yet, but he absolutely will before he leaves office.