Oh please. When she is coherent she is entirely scripted. When she's off the cuff, she speaks in weird slogans.
She was a prosecutor, so presumably capable of thinking on her feet.
Anyway, she only has to debate Trump and although he's a natural showman he's a not a good debater. If Biden hadn't been such an absolute trainwreck during their debate I think people might have noticed how poor Trump was a lot of the time - just waffling drivel and several times drifting off.
I think anyone not brain dead would make Trump look poor at a debate.
On the other hand, pollsters usually tell us that debates don't really count for much anyway and are soon forgotten.