An interesting question would be "what if Trump doesn't want to show up"? Would the Secret Service compel him against his will? In the extreme, what if Trump wants to fly somewhere with no extradition? Again, would Secret Service prevent that?

I do not believe the Secret Service would ever physically compel Trump to go somewhere (you know, other than whisking him away to safety in the event something actually happened). But I also don't believe they would interfere with a law enforcement officer with an arrest warrant - within limits.

They might insist that the LEO make accommodations to them so that they can always accompany him. They probably would not allow the state officials to place DJT in a location or facility where his safety couldn't be assured. But if Georgia law enforcement wanted to confine him in a hotel near the courthouse, then frog-march him into court, Secret Service would likely allow that to happen. They're there to provide protection, not insulate him from complying with law enforcement.

No clue whether they would do anything if he tried to board a plane to leave the country. Not even sure how that could happen, given that they'd have to buy a ticket for the Secret Service agent(s) and clear their firearm possession in advance - and surely the airline would not allow DJT to board the plane if he's skipped bail.