Paris Saint-Germain is a superior club in Ligue 1, so it is natural that almost everyone predicts that they will be able to become champions in Ligue 1 again. The percentage is not 100%, but when compared to other clubs, their chances of becoming champions are very high.
While in the Champions League they always have difficulty becoming champions, even their best achievement was only being runner-up and if I'm not mistaken they have only done it once. This new format will also be more troublesome, because to be in the last 16, 16 teams must go through the play-off round and only 8 clubs can automatically qualify. I don't know yet whether this benefits them or not, because in the next round it will be as usual, while they also often fail in the knockout round.
PSG is always the favorite team to win Ligue 1 every season, but the truth is that they can never be 100%. It is football, and anything is possible at any time. We have seen different cases in various leagues, like in the Premier League, Serie A, and Bundesliga, when unexpected teams won their league.
In the Premier League, when Leicester City won the Premier League trophy, it was unexpected because, looking at their squad that season, I don't think anybody thought they would be the winner of the Premier League. But in the end, they were able to win it.
Also, let's look at the cases when Napoli and Leverkusen won their league trophies. I think they were not the teams everyone expected to win the trophy. So in football, it just happens once in a while that an unexpected team will perform well and, at the end, achieve their aim.
I know that PSG's squad can never be compared to any team currently in the French leagues. PSG has the best squad, but I can't say 100% that they will win Ligue 1. They are the number one favorite to win it, but I don't think there is 100% assurance in football predictions.