While I don’t believe we’re anywhere near out of this yet, I don’t think he’d be anything like 2016 Trump if he loses again. At that point he’s lost twice (unfortunately probably to Biden again) and his supporters are filled with rage and vengeance but they also want a winner.
It could certainly get scary in a “American Troubles” kind of way, but if he stays out of the White House, I see his followers peeling away to shack up with DeSantis and other, newer goons to get their authoritarian fix.
As for jail, I think it depends: if he’s convicted snd sent to federal jail while losing the election, I think Georgia’s state level charges have a 50-50 chance of extending that stay, since I doubt ye’d be jailed for life. If the federal conviction fails, the state charges are much more likely to get dropped.