If it cut his face open we would’ve seen the cut
It didn’t even do enough damage to leave a mark
Let’s be real
Here we see King face is cut open. Fire is coming out of the cut, but he's unfazed.
Here's another scene supporting King's endurance.
Zoro states he hit King with slashes yet King is not bleeding. If King's body was too hard and durable to cut Zoro wouldn't expect him to bleed. Zoro also never said King was too durable to cut. Only his wings have blocked Zoro's attack.
Here the scene were the WG is testing his endurance.
King has high endurance.