Of course, Mbappe has joined the right team, because by joining Real Madrid there is a big opportunity for him to win a title that he has not achieved before. With Real Madrid being a strong and good squad, of course this will enable him to win the title he wants, what's more, he himself is a player who has good qualities in his role, of course Mbappe will help Real Madrid's attack line become more aggressive. Their chances of dominating the Champions League can already be seen, but even in football anything can happen and maybe there will be another team that can match Real Madrid, but I think that's unlikely.
Many people have been saying that for a long time, if Kylian Mbappe was at Real Madrid, he was at the right club that met his playing quality standards because at PSG he was just wasting his hidden talent because PSG is not a club capable of awarding prestigious titles and PSG's success so far cannot be separated from Mbappe's big contribution to the club so I think PSG will have difficulty achieving success again if Mbappe is gone and I'm not sure that in the Champions League next season PSG can reach the quarter-finals like last season since Mbappe is still at the club PSG's chances of winning the Champions League title if there is no Mbappe at the club
Mbappe at Real Madrid will make Real Madrid's performance sharper and the opportunity to win the Champions League title is wide open because Real Madrid's attack line will be stronger, but it's true, as you said, anything can happen because we also can't be sure what next season will be like. Either Real Madrid's mainstay squad will be in good health and not suffer any injuries during the competition because if one of Real Madrid's mainstay players is injured it will affect their performance and it will also affect their chances of winning again.