PSG's move to focus more on the Champions League is very appropriate because in Ligue 1 no team has been able to surpass PSG until this season and Brest itself will also be quite overwhelmed when having to face a team like PSG who in general have been much more consistent in playing in Ligue 1 this season. In addition, the next match for PSG is to be the home team with Brest as their guest and that certainly will not make PSG afraid because PSG is always better when playing at home with any opponent in Ligue 1.
PSG have been focusing on the Champions League games for the last few years, because they don't have enough competition in Ligue 1 to put more effort into it than they do. And PSG rarely had any problems in the group stage, the main difficulty starts at the playoff stage. I think Enrique will play to win against Brest, because they don't have such a big advantage over their opponents in Ligue 1, PSG will most likely try to score a few quick goals and then calmly bring this match to victory.
Almost every season their main focus is the Champions League, but unfortunately they have not been able to get what they have always wanted so far. They may be unbeatable and a superior team in Ligue 1, but in the Champions League there are many competitors who are even better than them.
Enrique has a difficult task to be able to bring Paris Saint-Germain to achieve success, it is not something impossible, but it will be very difficult for them to do, especially since some teams have very good strengths such as Manchester City, Real Madrid and others. In the early stages they usually find it easy to qualify for the next round, but when they enter the knockout stages they start to lose their balance and eventually have to be eliminated.