For some reason i can't change my vote. Oh well. But yes, i would say that she definitely has it. Ace and Katakuri have it, no reason Yamato wouldn't have it.
I don't think we have seen her infused it and used it in her attacks yet. (we don't see the lightning coming off her club like Kaido's, even though Yamato can use his moves).
If i had to guess then i would say that yes yamato definitely has CoC unlocked (there is no reason to doubt this because people younger than her already have it unlocked AKA Luffy).
Whether or not she can use it or infuse it in her attacks like Kaido i'm more skeptical, and i also don't know how her CoC compares to the Worst generation. I say this because i think that she hasn't had much chances to use and train it, you know with being held captive on Onigashima and all. Since experience should play a big part in how strong one's haki is, particularly in the case of CoC, as said by Rayleigh. And for Yamato it would be hard to achieve that all locked up on a island.
As for Yamato tanking Sasaki's cannons, i still don't know if its due to her zoan devil fruit, or her amazing genes being Kaido's daughter or her CoC Haki.