the best players should always play, regardless of age.
Who can say that Messi, Benzema and Modric are too old and should stop playing.
Real regularly wins the Champions League with such old players, and the Croatian football team won two medals at the last 2 world championships with Modric as the main player.
I sincerely hope that Modrić will finish his football career at EURO 2026, and to win any title in football, the experience and mental strength of the team is always important in addition to the individual quality of the football players.
It's difficult for me to say why Germany lost to Japan, but I think the reason is not only weak defense but also ineffectiveness in attack and it is obvious that this team needs some changes and new players in the team.
I am not entirely sure if Croatia would be able to get a title, but it is true that they have managed to shock the world with Modric as their best player and he is considered "old" for football. I get that if you are going to buy a player for a club team, you would prefer a younger player, why not get a 25 year old who has a bigger potential than a 35 year old, but when we are talking about national teams, that means you are going to need that player for a maximum of 5-10 games and that doesn't really matter if they are old or not.
This is why it's quite unimportant how old a player is, as long as we are talking about players that could end up with something decent in the end and provide for the club.