I don't see Victor Osimhen as a player that might have trouble playing in the EPL from his first season because he has the europe football experience especially while he was in Napoli. His level of experience and professionalism wouldn't take him more than a few games to adapt to the EPL, we saw Erling Haaland did it with City in his first season and the next despite haven't played in the EPL before. So Victor Osimhen wouldn't be any difference in adapting immediately. I really do feel for him too.
But Haaland played in the Bundesliga, then Borussia Dortmund was perfectly competitive with Bayern, rightfully one of the strongest teams in Europe, so he had no problems moving to the EPL, but Victor plays in the Turkish league, which is nowhere near the top European leagues, so there is some difference between the adaptations
Have tried to know why the bundesliga is kind of referred to as farmer's league by many football fans and the Italian Serie A is not? Here's the gig mate. The German bundesliga is heavily dominated by Bayern Munich in almost every season except for last two seasons ago that Bayer Leverkusen had an unbeaten run and won the league trophy which Bayern Munich has retaken it's position back this just concluded season of 2024/25. But this isn't said about the Serie A because it's highly competitive as the EPL with different teams having to win the league trophy in every season with a rare back to back champion. Osimhen has played for Napoli, now he's playing for Galatasaray doesn't make any difference about what he can do.