So I looked up the fight, and the story behind it is kinda crazy.
First, the fight promoters don't put on fights, they put on circuses. Someone already mentioned Logan Paul, that kind of crap. This fight was originally supposed to be in California, and was going to be Oscar De La Hoya vs Vitor Belfort. De La Hoya is a former champ, and Belfort isn't a boxer, he's an MMA fighter, and both are past their prime, so this was just meant to be spectacle. But California wouldn't sanction the fight, so they changed venues to a state that doesn't mind hosting super spread events: Florida.
Then De La Hoya got covid and had to drop out last second. Meanwhile, Evander Holyfield has been in litigation against the fight promoters for breach of contract because the fights they keep promising him keep falling through. Holyfield is like a billion years old in boxer years, so if he wants to get paid he basically just does these types of stunts. So since they need a fighter, now he's in, and maybe they can avoid getting sued (probably not).
As for Trump, best I can tell he's not going to be an actual commentator. Instead, for people who pay extra for what I assume is going to be the ultra patriot freedom maga package, you can watch the fight with "alternate commentary" with Don and Don Jr rambling incoherently into a microphone.