I feel like Kylian Mbappe would be on the left wing, Endrick as the center forward and Vinicius Junior on the right wing.
You are saying Endrick will be in the starting eleven quickly? Honestly I don't feel like that man.

Ancelotti prefers to keep this kind of young talents on the bench for a while and asks from them to be patient for their time. The same thing happened to Vinicius Junior also and it is happening to the new young talent Arda Güler as well.
This is why I'm expecting Mbappe to be at the centre, Vinicius Junior on the left wing. For the right wing, Rodrygo/Valverde can be preferred. However this is valid if Ancelotti prefers 4-3-3 formation.
If we see a formation with 2 strikers, Vinicius Junior - Mbappe duo might be seen and Bellingham right behind them.

These are just predictions of mine though so let's see...
Will there be a new format for the Club World Championship next season? Consider this tournament, La Liga, the Spanish Super Cup, the Spanish Cup, the UEFA Super Cup, the Champions League - it seems to me that there will be many opportunities for young players like Güler and Endrik to show themselves. It's clear that they won't push Mbappe or Vinny out of the starting lineup, but with so many games in the season, Mbappe, Vinny and the rest of the main players will be happy to give way to the rotation players and get some rest.