Yamato is revealed to have eaten a Zoan-type Devil Fruit and has transformed into their hybrid form. Kaido claims that Yamato was never meant to eat the said Devil Fruit, which took Kaido great effort to acquire.
From Hybrid Yamato’s appearance one could tell that she ate the Kirin/Quilin Mythical Zoan Devil Fruit.
The Kirin in Japanese, Qilin in Chinese, is a mythical hooved chimerical creature known in Chinese and other East Asian cultures, said to appear with the imminent arrival or passing of a sage or illustrious ruler. It is a good omen thought to occasion prosperity or serenity. It is often depicted with what looks like fire all over its body….
The Kirin / Qilin can sometimes be depicted as having a single horn as in the Western tradition, or as having two horns.
Japanese art typically depicts the Kirin as more deer-like than its Chinese counterpart.
In the Post-Qin Chinese hierarchy of mythological animals, the Qilin is ranked as the third most powerful creature (after the dragon and phoenix), but in Japan, the Kirin occupies the top spot. This is following the style of the ancient Chinese, as Qilin was ranked higher than the Dragon or Phoenix before the Qin dynasty. During the Zhou dynasty, the Qilin was ranked the highest, the Phoenix ranked second, and the Dragon the third.”
So, what does Yamato have in common with Kirin/Qilin?
The horns though Yamato has horns in human form.
The fangs, actually Kirin does have a dragon head, so it has fangs.
The claws, Kirin may have claws in the front legs, or may be just the hybrid form hands.
The ears, Kirin does have deer/horse ears.
The tail, some depictions of the Kirin do have a fluff tail, some of them have a horse tail, and some of them have a fluff end at the end of a dragon tail.
The flames, Kirin body is in flames similar to Dragons, Byakko, Komainu or some mythical Foxes.
Qilin is portrayed in white, like Yamato’s hair and seemingly Yamato’s transformation.
Furthermore the Qilin’s reputation could explain why Kaido specifically wants Yamato to sit as the Shogun.
Kirin is said to appear with the imminent arrival or passing of a sage or illustrious ruler. Luffy ascending to Pirate King?
The only reason why Yamato could not be a Kirin/Qilin:
The scales, Kirin always have scales, but Yamato may lose them in hybrid form.