The key here is Biden allegedly got 7M more votes in 2020 than Trump. This was a 4.8% lead following a polling lead of 7.5%. 5M of the 7 were in Calif and 2M in NY. This is why the electoral votes spread among the relevant states was only a few 10s of thousands.
If that 7% polling advantage is reversed, this is landslide territory in the battlegrounds.
7M stuffed ballots