I agree with you on that, because Mbappé can arrive in a very capricious way to a Madrid where basically he can't and shouldn't do things the way he wants, Madrid is not PSG and that was one of the reasons why they didn't want Mbappé to come to Madrid and I think that here the one who is going to make the difference without a doubt is going to be Ancelotti, because above all he is a gentleman who must be respected, everyone at Madrid respects him and knows that he is more than a coach, he is like a father to them, when he found out that Kross was leaving, Carletto cried, so Ancelotti is more than a coach to them, that's why I don't think that Mbappé will arrive with that emphasis of wanting to do whatever he wants.
Basically, Mbappe will not be able to do as he pleases, a bit like he did when he was at Paris saint Germain, in PSG he was the top player pampered by everyone and had no major rivals in his role, at Real Madrid he will become one of many top players and the starting place is by no means assured. So he better be respectful of the locker room hierarchies
I think that before doing that he should think about Ancelotti, because Ancelotti is a very good coach but he is seen to be very severe, so in this order of ideas things can be considered very good because this player, if he comes with great potential, must adapt no matter what, even more so now that Madrid is on a winning streak and here he must do what he is told and accept the group of players as they are, therefore things for him at Madrid only depend on him, I am sure that he can show everything he has but as long as he respects and adapts, perhaps things can be easy if he makes up his mind.