Even though older players are needed because they have experience, there are also levels of weaknesses they have, such as fitness when playing the full 90 minutes. Luka Modric was not played for 90 minutes in a crucial match because Ancelotti realized that his physique was no longer the same.
Most coaches only play three older players during a game and the rest will be played by much easier players. In terms of experience and mentality, older players will be much better and they can help young players to develop.
However, if you face a team that has a defensive and attacking strategy, older players will have a little difficulty keeping up because they rely on running and physicality.
From what Ancelotti has implemented at Real Madrid, it is quite clear that he does not rely too much on old players with a duration of 90 minutes in each match. That is why there are several senior players at Real Madrid who we often see on the bench before they are introduced into the match while the match is in progress and I also see that the enthusiasm and sense of optimism that young players have will also increase when they play with senior players. Although predominantly there are more young people who can make better defenses and attack on target.