If chelsea can succeed to sign him it will be a great deal for the club, their attack will be more stronger and they will comfortably challenge for the premier league title.
That is if he does not get injured.
If I am Victor Osimhen, I will be very selective of the club I play for and will not just want to move to any club because it is an English team. He is already very welcomed in Napoli and has no complain about the team, the coach, the management of the club and the supporters of the team in Napoli, so he may not be too keen on leaving to just any club that he knows will be difficult for him to win trophies in. He has won one very good trophy winning the Italian league, it is normal for him to feel the urge to want to win more and will want a club that he can win in. In terms of the competitions that Osimhen will have an opportunity to win next season, Napoli will play in more competitions than Chelsea will, so staying in Napoli is also a good choice.