When a team succeeds in winning any trophy which happens to be a major one, it's expected of the team to do their best in other to retain that trophy again. I'm football, it's believed that it's easier to win a trophy than to retain it because after winning a trophy, every other opponents you'll face in your quest to retain it will definitely know more about the tactics that helped you win which in response will do anything possible to stop you from conquering again.
Since the 2017/2018 season, there has not been a team that is as capable as Real Madrid. No team has been able to return to winning the UCL in a row. Only Bayern Munich and Ajax in the year have been going on for a long time. Bayern Munich winning in 1974, 1975, 1976 and Ajax winning in 1971, 1972, 1973.
Of course, with the arrival of stars like Mbappe and Endrick, I think Ancelotti is trying to defend the UCL Title. With a good financial condition, Madrid has a great opportunity to build a stronger team for next season.
When there is money, the club will become successful and that is what Real Madrid is using to oppress other European clubs, because they can buy any player that they want without a problem which is an additional advantage. Unlike Barcelona that is currently facing some financial challenges and cannot sign a new player to add to the team.
The probability of Real Madrid winning the defending the title next season is very high due to Mbappe and Endrick who are now in the club to strengthen and close whatever loop hole the club has. Ancelotti will be happy to continue winning UCL till he retires from Real Madrid.