Oopsss. That would be a scenario I never expected but I think you are talking about a potentially strong possibility. I think no matter what Mbappe should leave France and go to England and if possible he should enter a competition with Haaland. As long as he stays in France, there is no chance of him winning the ballon d'or. I think he needs new challenges now instead of money.
Yes, I agree with you if Mbappe wants to look for a bigger challenge then he should go to the Premier League rather than Laliga. However, if he wants to win the UCL trophy then he has to join Real Madrid. Mbappe will definitely leave Ligue 1 one day and go to another league. But I hope he goes to the Premier League because this competition is the best competition at the moment.
However, Mbappe is very much linked with Real Madrid, of course if he wants to reach the ballon d'or he will be able to achieve it if he joins Real Madrid. In Ligue 1 it is very boring to watch their matches because there is no other team that really has the same strength as PSG so every season you can guess that PSG is the winner of the Ligue 1 trophy.
But if he joins one of the teams in the Premier League then we will see quite fierce competition in the EPL every season because in the Premier League there are many top players there such as Haaland and Salah.