Any animal who's diet is 100% meat or 100% plants is pretty rare.

There are animals who definitely prefer one over the other, and there are animals that are much more suited for one over the other.

Basically you have Hypercarnivores (Typically called Carnivores), which have a diet that is roughly 70% or more meat on average. Basically every species of cat is one of these. Some canine species. Predatory birds. Tons of others. Dolphins are one a lot of people dont really think of.

Then you have Mesocarnivores (Either considered Omnivores or Carnivores depending on the perception of the animal), who's diet is roughly 50% meat. Most rodents, some canines. Foxes.

Then you have Hypocarnivores (Herbivores or Omnivores depending on the animal). Who's diet is 30% or less meat. Deer, Black Bears, lots of primape species, including humans.

Despite what their natural diet, hunting abilities, teeth, etc will show you. All of these animals can eat plants or meat. For example, a deer, if given the chance, and if it's hungry, will eat a rabbit. Generally this means picking at a carcass, since deer aren't really equipped to hunt them. Meanwhile, a Lion (like most cats) are not opposed to eating certain types of grass, even if they're more equipped for hunting prey.