For me, I think PSG management will not want to allow Mbappe to leave PSG as a free agent after they have spent so much money on Mbappe. PSG management might give Mbappe another lucrative deal that will make him remain at PSG. PSG has built its team around Mbappe, and it will affect PSG's performance next season if they allow Mbappe to join Real Madrid before the start of next season. But let's wait and see what will play out between Mbappe and PSG.
Did you know that Mbappe's contract will end in the next 30 days? meaning PSG can't do anything and Real Madrid is ready to bring him in for free, we know that Mbappe and Real Madrid already have an agreement this season, they are just waiting for his contract to end. Mbappe has no reason to reject Madrid because when he played at PSG he never won the Champions League trophy so by becoming a Real Madrid player he has the opportunity to make history. PSG could get money from releasing Mbappe if they find evidence that Real Madrid made fraudulent efforts in recruiting this player, I believe 100% that Mbappe will be a Real Madrid player in the next transfer window.
I'm very much aware that Mbappe will soon be a free agent, and he can decide which club to sign for, but 30 days is enough for PSG management to make Mbappe change his mind. PSG management can decide to promise Mbappe that they will buy him any players he wants at PSG just for him to commit his long-term future to PSG. We have seen several cases where a player will want to leave a club, but all of a sudden, the player will say that he is happy staying at his club. PSG can still do something in Mbappe's case; let's wait and see as the story unfolds.