If you look at Real Madrid's pre-season fixtures, they will face AC Milan in the near future, interestingly Real Madrid will face many big clubs in their pre-season matches. I want to see how they do in the pre-season matches, I won't judge them and conclude, but I will see the development they will show during the pre-season matches. There will always be a difference between pre-season matches and real matches, but it can be a reference even if it doesn't guarantee it.
We'll be shown some matches from big clubs as they prepare.
Real Madrid have new great players and they surely will add to the strength of that team, and maybe also add variety in terms of formations which can use of Real Madrid coach, because sometimes a coach often do experiments on his players. So yes, although that match is a friendly match but it might be good reference because the coach will try several formations. Also, interesting is that they will be playing vs Manchester United, if i'm not mistaken it's been a long time not meet since they last match in 2018.