I assume both sides have done their homework and their stances on vote by mail should be telling.
Obviously educated voters prefer Biden. So this would seem to strongly favor Trump in a higher turnout. Except this clearly includes a lot of poorer people, which may skew Democrat. Ultimately, they are probably more poor rural whites that could vote who otherwise wouldn't that would favor Trump. But it's perhaps not a great assumption that vote by mail will substantially impact turnout.