Paris Saint Germain, Monaco and Brest will represent Ligue 1 in the Champions League next season. By changing the format of the Champions League to a new format, Ligue 1 will get 1 additional slot for the team that will compete in the Champions League. However, I don't see them being able to compete there, because it is a difficult place, only Paris Saint Germain will probably be able to go further and even then they will still fail to win the title they have always wanted.
Compared to teams from other leagues, I don't see them being more convincing, because the competition in Ligue 1 itself doesn't have a good competitive level, so that will affect their performance in bigger competitions. Apart from that, in my opinion their mentality is no better than other league teams. I don't mean to underestimate them, but this is my assessment of several teams that will be in the Champions League representing Ligue 1.
In my opinion, the French League is one of the weakest leagues among the European leagues. The quality of football in this league is not very high, the players and teams are below the Champions League level.
For a few seasons PSG performed well, among the other teams there was no team that had a chance of winning the title, perhaps they have not been very successful in the last 20 years. The 3rd and 4th teams in the Champions League will be easy opponents for other teams

There are very high-quality young talents in the French league, but PSG is currently working so well that it is collecting young, promising 15-16-year-old French players into its infrastructure and releasing them to the market a few years later. The latest example of this is Zaire-Emery. That's why other good young players cannot leave the infrastructure. When teams like Monaco and Marseille move away from their policies of transferring good players, this becomes an inevitable end. In addition, PSG is so financially strong that the team that can compete with them is not located in France.