King stated his durability is beyond that of dinosaurs(Queen) and dragons (Kaido).
That's flame mode King durability.
King's wing, which is part of his body, clashed against Zoro's 3 swords style attack without taking any damage.
That's flameless King.
The part of the attack that hit his head cut his mask but only caused him a tiny amount of superficial damage on the surface or a hit mark.
Regardless, flameless King took less than Kaido. That's a much stronger attack than the one Zoro used on Kaido that easily cut through Kaido's body and scales and made him bleed a lot.