Zoro's powerup vs King was just him learning to tame Enma and nothing more. He released all his haki, without fear of dying, and inadvertently unlocked CoC. King questioning him about wanting to be King and Zoro responding yes, was just him acknowledging the fact that he wants to reign supreme above all swordsman.
Now this fight vs Bommers, is him learning to use CoC in his attacks, without necessarily going all out. Something he couldn’t do before. But it did have the added bonus of letting his body get used to the feeling of what CoC is, hence Gaban's shit. That's why Zoro's current flashback when it comes to CoC was a Mihawk & Gaban flashback, and not Kaido & King [even though they both mentioned it].
So no powerup this arc, so far, just him learning to regulate his powers, without going all out, which makes his Conquerors Haki attacks even stronger.
Oda is a hack writer, but I won't hold a gun to his head for this one