That is how it always is and whether Osimhen plays as good in any other team as he did for Napoli, as you said time will tell. There are players who have no problems whatsoever to always show their best performances regardless of the team they are playing for. I don't know whether Osimhen is that kind of player, but I believe he is good enough to have a place in many top teams. But would he be able to make it into the first eleven players of Real Madrid? I don't know and yet he has the score statistics that drew some attention to him.
Evaluating the Nigerian striker from his past clubs will show that he has succeeded in the French club Lille and is having a good time in Napoli. He is an aggressive player that perfectly suits the Italian league but I think he will also do well in Spain. Playing under an experienced coach like Carlo Ancelotti would bring out the best in the Nigerian striker. Most players will excel anywhere if they play under a good coach and a good team. Real Madrid has some of the best creative players in Europe who will constantly create goalscoring chances for the Nigerian striker. Karim Benzema excelled in Real Madrid because he had the support he needed to score.