From a traditional understanding of debates, Kamala absolutely whipped him. if it had been a boxing match, his corner would have thrown in the towel by the three-quarter mark.
Of course, debates no longer operate under a traditional understanding. Trump did nothing that will turn off his base (and probably can't do so at this point), so that limits his downside. But Trump did absolutely nothing to appeal to anyone outside of his base and did a lot to turn them off. He came across as an whining, petulant, angry man who has nothing very little to offer in terms of new ideas. Kamala, while I'm not sure she nailed it, certainly came across as the far better candidate unless you want someone who is still angry about past elections and sees America as a hellhole.