Every team has a different way of building their team and indeed PSG chose the wrong path because they didn't want to go through the process and rely on the power of money they have to buy star players and hope they will achieve achievements on the European stage, that's the wrong thing and Even Mancheter City used to be like that before they finally went through such a long process that it was only last season that they managed to become CUL champions.
Likewise with PSG at the moment, especially because in the French League there are no fierce competitors so PSG cannot measure its strength.
Obviously it will be quite difficult for PSG to measure its strength if its competitors are still quite weak like now, because in the French League PSG can still win with second-tier players and even without star players. But in the UCL, everything must be truly complete for a team that wants to become champions there, from a great coach to truly talented players. And cooperation between players is also really needed because PSG has also proven itself that having several star players does not guarantee success in the UCL.
I don't think it's right to talk about PSG and their playing style in the Champions League and the French League at the same time because we know PSG is the team that usually has a high chance of winning the French League because they are not many teams to start racing this PSG but in the Champions League everything is different for them and they will need to start the competition with teams like Real Madrid with much better player they have.