2 clubs from the previous europa league now meet in the Champions League 
Obviously this is a little interesting because on paper Napoli is certainly better, but seeing the current condition of Frankfurt they also cannot be underestimated because they could just bite like last season in the Europa League. Frankfurt's defense is sometimes very difficult to penetrate and this is a good test for Napoli, which is very good in terms of attack and goal productivity.
Napoli will not be so difficult to face Frankfurt in the Champions League this season even though what you say is true too, but Napoli on the other hand also has the ability to dismantle any team's defense this season. Even though the two of them have yet to meet in the Champions League this season, I see that in Serie A Napoli have often never made a fatal mistake this season so that has made Napoli look more convincing to win against Frankfurt in the Champions League this season.Obviously this is a little interesting because on paper Napoli is certainly better, but seeing the current condition of Frankfurt they also cannot be underestimated because they could just bite like last season in the Europa League. Frankfurt's defense is sometimes very difficult to penetrate and this is a good test for Napoli, which is very good in terms of attack and goal productivity.
I wouldn't take it as if it were easy for Napoli even if on paper they are the favourites.