Conte wanted him instead of a younger Victor Osimhen that already knows the league very well therefore Lukaku has alot of presume on him to prove Conte right. It doesn't matter what he has done in the past, he has a task to make Napoli better and win their games. Conte is a very vocal coach and if Lukaka doesn't deliver him goals, he's going to begin to have problems with him. Conte has a history of falling out of love with his players. Napoli plays Cagliari for their next match and Lukaku needs to keep scoring for the manager to use him more. He doesn't have a good relationship in his previous clubs and the fans know this therefore he needs to make them happy to get them supporting him
Osimhen is no longer played by Conte at Napoli, and currently Lukaku is his replacement. I think this is the best choice for Conte to make, because even though Lukaku is quite old, he has many advantages and experience that other players at Napoli don't have. So with this of course Lukaku must not disappoint the trust that Conte has placed in him. Therefore, Lukaku must be able to score lots of goals for Napoli. Lukaku has proven this in the previous match when Napoli faced Parma. Even though he didn't play for too long in the match, Lukaku managed to break the deadlock and was able to score an equalizer for Napoli in the final minutes of the match. So this is strong evidence that Lukaku is still a quite sharp attacker. Therefore, I think Lukaku's career at Napoli will most likely be better than at Chelsea or at Roma.
And yes, in the upcoming match Napoli will face Cagliari. I think Napoli will dominate this match. Because if you look at Cagliari's performance this season, I think it can be said that it is not good. Because in this new season Cagliari has never received a single ministry. Apart from that, if you look at the head to head record between Cagliari and Napoli, it is clear that Napoli is superior. Because in the last 5 matches Cagliari has never won against Napoli. So with this in mind, I think betting on Napoli in this match would be better.