Since Kylian Mbappe has been strategically retained for this season at PSG, I think Mbappe will not play at his best in every match. But PSG have done a great job by signing Dembele, I think Dembele is undoubtedly a fantastic forward.
Dembele is also expected to be able to help other players at PSG like Kylian Mbappe, because PSG is now different from last season so that every player at PSG is expected to be able to maximize their potential and abilities in all matches so that PSG doesn't get worse this season. Tomorrow PSG will host Lens at the Parc des Princes, and as we know that Lens is not a weak team in Ligue1 so PSG must play better if they want to get full points at their own home for tomorrow.
Talking about Dembele, he is a very complete player in terms of speed, dribbles and good finishing. He can play on both wings and it depends on which side Luis Enrique puts him on. If later he enters as a starter, it is likely that he will occupy the right winger position, then Mbappe the left winger, and Goncalo Ramos will become the main strikers. I think it will make it easier for PSG to win the game than to bench one of those players again. PSG's responsibility is getting heavier because they are required to win this home match perfectly and if they still lose, of course things will heat up in the locker room and Luis Enrique's fate could be in danger.