Yeah Osimhen prefers to stay and extend his contract with Napoli this means that Osimhen cannot make a decision in the next few seasons, unless Napoli wants Osimhen released, as you said, Osimhen's performance has not been optimal this season so his interest and market value will definitely decrease so there is a possibility that we will see Osimhen play longer in Serie A. This season Osimhen only scored 12 goals and this is proof that its performance is declining but Osimhen is still young he still has a chance to improve his performance next season.
Yes, that's because Victor Osimhen was offered a salary increase at Napoli so Victor Osimhen chose to sign a contract with a higher value and Napoli also tried to retain this key player before his contract expired because Napoli also didn't want to lose Osimhen, but unfortunately after Victor Osimhen signed The new contract actually reduces his potential at Napoli, he doesn't seem as aggressive as last season and his total goals are also not as many as last season, perhaps because of Victor Osimhen's absence in several matches due to injury, which affected Osimhen's performance.
Napoli itself is actually willing to sell Victor Osimhen if another club wants to enter into an agreement on the price set by Napoli which of course is pricing Osimhen at a fairly expensive price and Chelsea is very interested in bringing in Osimhen even though they have to dig a little deeper into their pockets. But we are also yet to be sure of Osimhen's performance still good when he is in a more difficult league if his performance declines of course it is a big loss for Chelsea, indeed he is still young and his potential can still be honed but if it doesn't suit Osimhen's playing style I think it will be difficult to find the right rhythm and restore his performance Osimhen as before.