Perhaps the price is inflated on purpose, so that no one could not buy the player, or at least did not try to do so. I think he can't even cost 100 million euros, maximum 60-80, but not 100. There is also information in the media that Chelsea want to sign this player, but for now they are watching the situation and waiting for the player to decide on a new contract with Napoli, if he does not sign it, then most likely Chelsea will start working on signing him.
Napoli management wants to keep this valuable asset for a long period of time, preventing him from leaving to another club in order to achieve joint success in Serie A. I think it is very natural that Napoli management set a high price for Osimhen, they know that there are only a few good number 9 strikers at the moment. This Not only Arsenal and Chelsea are interested in recruiting him, Real Madrid and SPL clubs are also interested in pursuing his signature.
However, this is just a rumor that cannot be relied upon, what is clear is that Napoli will not let Osimhen go at a cheap price. Moreover, if Osimhen manages to defend the Scudetto and is going further in the UCL, the price will definitely break the transfer record.