Playing at a big club is inherently risky, and it's rare to get regular playing time until the coach truly trusts you. Hendrick might face the same problem as Rodrigo, but we can see Xabi Alonso also utilizing the abilities of young players to develop the team. If he has the option to join another team to maintain his chances of playing for the national team, it might be worth considering, but staying at Real Madrid at such a young age could also be very beneficial for Rodrigo.
What you say is true, as Xabi Alonso is a coach who rarely neglects young players, although he also favors players with experience at big clubs like Real Madrid. However, as for the two players you mentioned, I also think they would be very well served if they stayed at Real Madrid, as Xabi Alonso would certainly give them playing time, although we may not know if they would only play a few minutes after regular substitutions in any given match. Ultimately, however, young players like Rodrygo and Hendrick will never be wasted if they remain at Real Madrid next season.