Tbh, I don’t know why Oda hasn’t created powerful foes irrelevant to Luffy for Zoro to defeat on his path to the WSS.
Guys like Weevil, Kuma (if he hadn’t ended up as an ally), or even Law could’ve been cool names on Zoro’s resume in another timeline.
People say that Katakuri to Kaido was a massive jump for Luffy, but that also involved a training arc, the help of several people, and multiple further power ups.
I don’t expect that Zoro vs. Mihawk will include all or any of that. At best, Zoro will forge a kokuto in the middle of the fight.