Real Madrid already has the best players in it even though they are reserve players, Carlo Ancelotti does this so that he has lots of choices because if there is an injury storm like last season he doesn't need to worry because he is very good at rotating players.
I think that even though Real Madrid recruited a lot of players, they didn't spend much on their budget because they got Mbappe for free, at least 150 million euros he could spend on other players who certainly have good potential.
Real Madrid has been known to be quite clever in recruiting the players they want so far, so that the team's strength always looks more stable every season. Apart from that, what you say is also true in that Carlo Ancelotti is also quite clever in managing the main players with reserve players so that Real Madrid does not face excessive difficulties when several players suffer injuries before the season ends. This means that Carlo Ancelotti at Real Madrid can implement quite effective strategies, so it is not surprising that Real Madrid continues to be taken into account in the UCL competition every season.