Sending the FBI to arrest Trump and drag him back to NY to serve a state sentence might be easier said than done in a few states I know of. I don’t think it would be a good idea for Trump to try it and I don’t think he would consider it, but a blue on blue confrontation between the FBI and state or even local law enforcement is not out of the question. Heck even the Secret Service probably wants a piece of the FBI’s ass.
Article IV, Section 2 of the U.S. Constitution
“A person charged in any state with treason, felony, or other crime, who shall flee from justice, and be found in another state, shall on demand of the executive authority of the state from which he fled, be delivered up, to be removed to the state having jurisdiction of the crime.”