Mbappe is a newcomer so Ancelotti will not change the position of Vinicius Jr and Rodrygo who are old Real Madrid players as wingers while what Ancelotti needs is a center forward so whether he likes it or not Mbappe must be ready for that position because from the start the coach must have said it and Mbappe must be ready for all the consequences, but in my opinion it won't take long for Mbappe to adapt to the team he is basically a pretty great player in the striker position he just changes his position but has the same task.
Mbappe is new and if Ancelotti should risk the position of replacing Vinicius and Rodrigo position will only put the club at more risk because they were there before Mbappe and they were playing better before he later joined so he was just like a plus to the club, mbappe needs to be more than ready because everyone is looking to what will happen when he starts playing forward-center. he should know that his going there to play a serious game and not for the fanciness of playing for real Madrid, and with time am very sure that his going to take proper shape in Madrid changing leagues is what is currently affecting him but time will tell exactly if the changing in the league is what is affecting mbappe or is becoming lazy but I still have faith in the young man that he will do what is right when the time is right, just like the case of Benzema, mbappe will surprise a lot of people.
But if you really want to be bolder, I don't think it's wrong when applying a 4-3-3 scheme but the position is slightly changed where Mbappe is moved to his ideal position and Vini is placed more as a targetman if you really want to try variations because after all, by looking at the current conditions, although Mbappe and Vini's performance is still quite good, there is a little less than Mbappe when he is a targetman because he is a striker who is a runner type on the side of the field.
This does not mean that this replaces the whole but this only slightly changes the scheme so I think if it is possible this is still very doable for Ancelotti but until now even though there have been several matches that did not match expectations but it seems that Ancelotti is still very satisfied with the conditions where 2 strikers or 3 strikers where Mbappe's placement is forward.