I’m sure that decision will get appealed.
Delay is probably all he can do.
This question of presidential immunity reached the Supreme Court again during the Clinton administration. In 1991, Paula Jones, a former secretary in the Arkansas statehouse, filed a sexual harassment lawsuit against then-Governor Bill Clinton. Litigation was still ongoing when Clinton was inaugurated as president in 1993. As President, Clinton claimed that the office of the President granted him immunity from the civil suit and warranted suspending the case until he left office. The Court heard oral arguments for Clinton v. Jones in 1996 and reached a unanimous decision in 1997. The Court ruled that a sitting president is not immune from federal civil lawsuits for events that occurred before they were in office. In a May 1997 op-ed, the New York Times editorial board argued that the decision reinforced the constitutional principle that “no American, not even an incumbent President, is beyond the law’s reach.” While this was a landmark decision, the decision did not address whether a sitting president is immune from civil lawsuits in a state court.
President Trump may have a path to at least delay many of his current civil suits as the courts decide whether he can be sued in state courts. With so many cases pending, it may be years before the question of presidential immunity is completely answered.
https://constitutioncenter.org/blog/is-president-trump-immune-to-lawsuits