PSG already got what they needed to have. In the last season, they had superstar players but they didn't have a coach like Enrique in this team to help players have better teamwork and they have it. Also, Enrique is experienced enough to make PSgeven win the Champions League title.
But other than this, they have to give Enrique some more time and provide him the players he needs, Mbappe leaving PSG was harmful for them.
PSG will still have difficulty competing in the Champions League because League One is not very competitive, this is the main problem. What PSG hasn't done in its ambition to win the UCL league trophy, it seems like PSG has done everything, from bringing in star players to a very experienced coach like Enrique, but still failed.
The Champions League competition is very tough and you have to have a very strong mentality too. In League One, only PSG was superior so they didn't have too much pressure to get the League One trophy, but when competing in the Champions League they were under so much pressure that in the end they weren't strong enough to withstand that pressure. This is very different from other leagues which have very tight domestic leagues, which makes them mentally strong when playing in the Champions League.