Actually there is a very real scenario he's been laying out right in front of everyone in plain sight where he can attempt to steal the election.
His voters will vote in person leading to the Red Trump mirage on election night. He will be in the lead late into the night and even the next day. Then the Blue shift will happen with the mail in vote like it did in the 2018 senate race In Arizona. The Republican was ahead by 20 thousand or so votes then the Democrat won with the late surge of mail in ballots.
This is where in this period HE WILL CLAIM he has won and the election is being stolen from him. The Republican lawyers and courts in these swing states will stop the counts to investigate the "fraud" that is being claimed by the president and Fox News. His supporters will storm the voting facilities demanding he be declared the rightful winner.
The cases will be kicked up the Federal court systems that he has filled since 2016 and get the newly confirmed Supreme Court to rule in the Republicans favor like they did Bush Vs Gore.
The ballots will be tossed and the earlier Trump leads in a few vital swing states will be certified handing him re-election.
This article is very long but I think is a very real possibility. I hope I'm wrong but at this point........