The UEFA Champions League final is for the big boys and for strong clubs that have become the main winnings, usually settled with strong tactics. Bayer Leverkusen was considered untouchable not until they got thrashed by Atalanta in the Europa League final. This was absolutely a positive result and we know how determined they were during the competitive form they developed.
The final is for big teams that are very good in the field and also lucky to win their matches. Sometimes, it is not the best teams in the tournament that do emerges as finalist, because some of them might be marge in either semi of quarter finals which we have seen in the just concluded Champions League where Manchester City and Madrid that are considered the best teams and the favorites in the tournament were merged in the Quarter final and one was eliminated; while some teams will just be lucky by draws as they will be merged with teams they can easily defeat and get to finals.
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.
I think Mbappe will be a player with discipline in Madrid because it is his dream team, he will do his best to make histories and brake records in Madrid so that his name will always be remembered in the history Madrid just as other big players that has contributed positively to the team.