I’m sure that won’t be an important factor in the final at all.
If you look at these old Real players like Modric, Kroos or Casemir, they actually play like young men and their age doesn’t affect their game at all.
It doesn't matter how young or old a footballer is, but how good a footballer he is.
These Real players have been playing together for a very long time, they know each other very well and have a lot of experience. That will be one of Real's advantages in the final.
For LIverpool players it will be a disadvantage that they will have less time to rest and prepare before the final.
They do not play like young players to be fair, because they are veterans and veterans have this experience with them which keeps them consistent. Experience gives consistency even during finals of UCL that is the most important thing. If you are young and talented, even if you are seen as a better player, you could play a terrible finals game because you could be scared, or excited, or nervous and many other things.
But, when you are a veteran, you will not have any of that, you will be able to play like it's a random regular season game. This is how they have been able to beat all those teams so far as well, with experience and calmness even in the face of losing.