It is not yet certain whether Mbappe will stay at PSG or move to Real Madrid in the upcoming summer transfer window. A few days ago there were rumors that Mbappe is going to extend his contract with PSG until 2026. If Mbappe extends his contract with PSG until 2026, how will he move to Real Madrid next season? Anything can happen with Mbappe's club change. If Mbappe doesn't extend his contract with PSG next season, Mbappe's club change could be a big blow for PSG because Mbappe is one of PSG's most reliable stars at the moment, so it's natural that his club change will definitely not be good news for the club.
By looking at the situation of their contract extension where Mbappe is currently extending the contract but with a note that Mbappe can be sold next season I think this is proof that this contract extension is only to secure PSG's money because for Mbappe himself sooner or later he will leave.
On the other hand, as for when he goes to Madrid or not, actually it is not a certainty but seeing the price conditions of Mbappe I think only Madrid can bring Mbappe even though there are still Arab clubs but Mbappe will not want to be there so many believe Mbappe to Madrid.