The phrase "in the wild" means "in nature". Use this phrase to talk about animals and plants that are living in nature, rather than being kept "in captivity" by humans in a zoo, a garden, someone's home, etc.

In the wild, they can grow to be over 4 meters long.

Interestingly, we sometimes use this expression now to talk about things that people make like products or computer programs:

Everything seems to work, but we won't know for sure until we see how people are using it in the wild.