I think that too, but not because "he is like a wrestler" or something like that. He is a total coward.
The reason is simply the polls. Now he thinks he have a tiny chance. When election day comes closer and he realizes he is losing in polls, he will beg for another debate. Not because he thinks he will win, but because he won't have anything to lose (in his mind, of course. Because every time he opens his mouth, it's like a circus and he looks like a clown).
In fact, he did the last debate because polls were showing Kamala winning. He badly lost. Now he will need to make another one when polls tell he is gonna lose. Whatever it may be, the eternal angry crazy racist will simply expose himself again to the public.
What will be the next crazy stupidity coming out from his mouth? That's the real question. Bets are open.