Apparently, this is a thing in Serie A at the moment. https://www.espn.co.uk/football/italian-serie-a/story/4692513/serie-a-will-decide-scudetto-winner-by-playoff-in-case-of-tie-in-the-table
Strange that there is no mention of this in the 'Rules' section of Serie A in-game. Or maybe I'm misunderstanding.