Here's what EA had to say.
Read More: FIFA 21: Will I Need A Disc To Play On PS5 or Xbox Series X If I Upgrade?
What If I Upgrade From PlayStation 4 To Xbox Series X, Or Xbox One To PlayStation 5?
You cannot upgrade from one platform to another.
Meaning you can only upgrade from PlayStation 4 to 5 and Xbox One to Xbox Series X.
For more articles like this, take a look at our FIFA 21 page.