How do I set the depth buffer resolution?

I’m optimizing a game for mobile devices. One of the suggestions they give (see Oculus) is to build scenes with a 16 bit depth buffer resolution. I haven’t found anywhere how to do this. How do you do this?

You are looking for this:

I mistakenly excepted the first answer, but this is not correct. I am looking for the depth buffer resolution for the whole scene and not for a render texture.