NO!
As usual you don't have a clue about American politics.
If Biden steps down in time that means the entire ticket steps down and there can be an open convention.
In an open convention Harris wouldn't have a chance.
It would be between Newsom, Whitmer, and maybe Klobuchar.
Personally I prefer Whitmer but with such a short campaign name recognition is more important, and Newsom would be the natural favorite.
Newsom would murder the convicted felon in the general!
Saying all this, unfortunately Joe Biden bless his dear heart, is a very stubborn old coot, and it will be very hard for him to step down.