Regardless of anyone's assumptions about this, if Mbappe wants to win titles in the domestic league and Champions League next season. So Real Madrid is the more appropriate team for him in that regard, even though other teams are also more appropriate, such as several teams in the EPL. However, considering the competition and the very different weather as you said, the consideration might be quite correct if Mbappe wants to choose Real Madrid as the team that will make his career even more brilliant than it is now.
Madrid's condition should be able to support that. But I also didn't expect too much because there were some players who went to Madrid and failed. Historically and in terms of the strength of the League, it seems that French clubs have not been able to compete at European level. This season it seems that PSG were not so good when they started the league. Currently PSG's position is only at number 5 even though the difference in points is quite small.