According to several sources from Spain Mbappé just asked to PSG to be sold to REAL MADRID for this January.
Right now I wouldn't want to see him move to Madrid given that Vinicius Jr and Rodrygo have upped their game. Mbappe's arrival would mean Rodrygo would have to go back to the bench since he (Mbappe) does not want to play in the centre forward position.
Perhaps Liverpool or Manchester United may try to approach him.