I don't think if he stays in Napoli for many weeks because there are some teams that want to hire Osimhen for the net season if they decrease the orice for this player and for some teams like Real Madrid, Osimhen can be a good alternative option.
For Real Madrid getting Osimhen for the asked price by Napoli doesn't make sense at all since they could get Mbappe from PSG for the same price. I even think PSG are ready to sell for any price more than €100m since they will lose him as free agent next season. Osimhen contract will not due soon so Napoli will not reduce their price.
Yes, it is very possible because it is unlikely that Real Madrid will be willing to spend a lot of money to recruit Osimhen from Napoli because their target is Mbappe.
But the Mbappe transfer drama is very long and Real Madrid really need a striker to replace the position left by Benzema, this is a little difficult I think.
Napoli don't seem to want to let Osimhen go, that's why they set a high price. In my opinion, it's really not worth it for Real Madrid to sign him and I think it's better to wait and keep chasing Mbappe.