That depends on napoli whether the club is willing to sell him or not. As far as i know that if napoli only accepts the offer that will be surpassing the clause release. it has been clearly stated by the napoli president if he will always reject any transfer amount that will be less then what he has expected.
I know that if such amounts will not be possible to be bought by another club. Even some clubs like manchester united and chelsea won't even spending beyond 100 m anymore.
The chance for osimhen to stay even longer in napoli is bigger than leaving from the club. Real madrid needs to get a replacement for him but i don't even think if real madrid is willing to spend beyond 100m to get him to the club.
Napoli is very harsh with its decision about osimhen while sometime it's also become inconsistent caused by its always changing its decision regarding osimhen.
Sometimes napoli said yes and in another time said no about him.