I think I disagree here, because Mbappe is too good to not be able to adapt to tougher environments or leagues. There is a reason that he is already in the top 20 of the Champions League goal scorer list and also scored 38 goals in 68 games for the national team. His goals aren't only scored against Ajaccio, but against the best teams in the world on a regular basis. I wish he would go to a club in the Premier League as I think that should be the place for him to improve even more.
Yes, Mbappe has already shown himself in different conditions and everywhere he was successful. He is not a "rising" star, but a long-established one, and I am also sure that moving to any league will not worsen his results.
As for moving to the Premier League, it would be interesting to see (how they beat all records in a race with Haaland), but this is extremely unlikely for many reasons.
Indeed, basically Mbappe will still be fine if he leaves for another club other than Real Madrid but the problem is. If at his new club it will still be difficult for the club to win the title, then it will also only be useless, because at PSG also Mbappe still promises to win the title for Ligue 1 but not for the Champion League. So, at this moment if Mbappe leaves, then at least the club can guarantee to be able to get the Champion League title and yes, at least Real Madrid is among the clubs that can provide this guarantee.