The English idiom is “I could eat a horse” expresses an intense hunger or appetite.
This expression is often used when someone is veeery hungry and could eat a large amount of food. It is of course not meant to be taken literally, as the idea of eating a whole horse is quite absurd. Rather, it is a playful and hyperbolic way of expressing a strong desire for food.
In French, the equivalent expression is “J’ai une faim de loup,” which translates to “I have the hunger of a wolf.” This expression also conveys a strong hunger, but with a different animal as the symbol. Wolves are known for their voracious appetites and their ability to hunt and eat large prey, so the image of having the hunger of a wolf is quite vivid and powerful.