Usually Dembele and Kolo Muani should be able to assist him a lot. If they are all in their best form they can be one of the best attack lines in Europe. But it is easy to anticipate that they will lack consistency. Dembele has never managed to be consistent for more than two months I believe and Kolo Muani has played amazing in Frankfurt, but still owes the proof how he will be doing over the course of a whole season in a club like PSG. The league shouldn't be a problem for him, that is nothing new, but the Champions League as far as I know is new to him and he was pretty bad last game.
Both Dembele and Kolo Muani are two exceptional talents that can help PSG up in the champions league, they don’t need to depend on Mbappe to have them go that far. In fact I think they play better now than when they had too many stars. Aside this two, there players like Asensio who has the highest trophies in the competition and also Goncalco Ramos who is one of the most sought after strikers they need. This should make PSG go far but that is not the case. pSG do not have any senior player as midfielders, that was one thing though, they need to add somewhere