I think he should leave Napoli considering his future. Osimhen is a player whose talents I have no doubt about. He meant a lot to Napoli but they couldn't use him properly. His dream was to play in the Premier League, he said this at every opportunity. I think he proved himself in Serie A. The Premier League could be next. Chelsea was interested in him. I think they will prioritize his transfer because they want to build a better squad next year.
Currently Osimhen has indeed asked Napoli to sell him and Napoli who currently needs a lot of money to support Conte of course does not mind selling Osimhen if there is indeed a team that wants to buy him above the price of 120 million euros, but so far the big European team is reportedly starting to withdraw after Napoli priced Osimhen at a high price, Napoli is currently no longer prioritizing to keep Osimhen at the club not because he has experienced a decline in performance, but because Conte is more inclined to be interested in other strikers who are indeed asked to be bought immediately by Napoli, Lukaku is one of the priorities that Conte wants to bring in next season to become Napoli main striker.
One of the clubs that really wants Osimhen at the moment is Arsenal and Chelsea, but Chelsea rejected an offer from Napoli to exchange players between Lukaku and osimhen because in addition to asking for Lukaku, napoli also asked for a considerable amount of money as a requirement, so indeed Arsenal is a strong candidate to get Osimhen, but reportedly currently Arsenal is asking Napoli to lower the selling price of Osimhen so that it can be completed Deal.