He has the power to do something federally to make it ‘not illigal’. However this is not the same as making it a declared legal right. Technically states could outlaw alcohol today too, and you do find ‘dry’ counties out there, but most don’t want to be left out of that sweet tax revenue.

That all says, even if Biden could wave a wand and make it fully not illigal federally, if your state says no then you’re stuck anyhow.