I am afraid I have to admit Trump out worked Harris. Where she would do one rally Trump would do three and like a steamroller he just didn't stop. Despite his advancing age. And I think he has a much more developed political thinking than he is given credit for. All his playing with names, slogans (MAGA etc) his "working" a day in Macdonalds, or driving a garbage truck, in response to the Harris campaign, they were memorable skits.
Could the outcome have been different if Harris had been on the campaign from the start, rather than starting when Biden stepped aside, I am not at all sure. And the polls that were against Trump were wrong on the night, on the only poll that actually matters. Trump didn't slow in response to bad polling, perhaps Trump had his own polls, perhaps they knew not to trust the national polls. Whatever, Trump won quite easily in the end.