As evidenced by Sanji’s interest, it is clear that she’s considered at least in-universe cute, but she has a face and general look that is markedly different from the other “cute” One Piece girls.
One could argue that Nico Robin also fits this bill.
I will agree that Robin isn’t a Nami clone, but her look still blends in with the other One Piece girls, ESPECIALLY post-time skip. (bangs! why did her bangs have to go?!)
Perona’s design stands out in a way that so deviates from the other “pretty” girl character designs, that even if the other women don’t all look EXACTLY alike, Perona’s presence makes them look like Nami clones, compared to her.