Referee mode is one of the most wanted modes for FIFA franchise. FIFA fans were always asking EA for adding a Be A Referee feature to FIFA games since FIFA 07.
This feature could be possibly available for the upcoming FIFA 21 game. a game mode where you can create your referee character, go through the refereeing instruction, learn on soccer refereeing, referee matches and experience a ref career life. Such a feature, could be giving you the ability to control the referee on the pitch and decide on free kicks, showing cards, offsides and penalties as a professional ref.
You can request this feature (the Referee Mode) by writing your wishlist for FIFA 21 and telling EA why such a game mode could be interesting for FIFA 21.