If Texas had 77-80% turnout could Biden have flipped it

[President Punxsutawney Phil]

It really depends on where the additional turnout is from.

For example, Pennsylvania had turnout increases in both 2016 and 2020, but in 2016 most of the additional turnout was in rural, white-majority counties (with relatively few voters with higher education), whereas in 2020 it was mostly in suburban, college-educated counties. This resulted in a Republican victory in 2016 and a Democratic victory in 2020.