The debate being rigged, or who "won" is not actually relevant. What is relevant... 1) Did anyone change their mind about who they will vote for (don't think so to any significant extent) 2) Did media bias get exposed (a little) 3) Did Kamala's bitch face make her more or less likable as the next ruler?
1) Might have made likely voters more/less likely to turn up. 2) Yes, but only to Trump supporters. 3) Only unlikeable to people who are struggling. Her optimism was effective.