Well, but Real's players are also significantly older than Liverpool's team. That could make up for this disadvantage for Liverpool. Liverpool now has two important games left this season (last league game and CL final). For these two games, the highlights of the season, they will once again put everything on the line, no matter if they are physically and mentally drained or not.
Old age players will not be a problem for Real Madrid in the final. Real madrid players like Benzema and Modrid have long experience in the Champions League which will surely give encouragement to all players in the final. for Liverpool they also have experience playing in the final in the Champions League, of course they want to repeat the success in 2018-2019.
Liverpool have younger players than Real Madrid and has experience in the UEFA Champion's League final, this is a big plus for them going into the finals.
I think Real Madrid's defense is not strong at all and the Mane and Salah will run riot at them. Real Madrid will have to depend on their old but effective players like Modric and the miraculous Karim Benzema to get the job done.