Does the engine render faces that can't be seen?

In my game the camera has a fixed angle, so geometry can only be seen from one side.
The game uses a custom material to fake light.

So, does the engine process the material on the whole mesh, or just on the parts of it that are seen on camera?

I was thinking I could modify my custom material to only apply to the camera facing sides of the mesh, but now i’m wondering if that’s really necessary, or if the engine already does that.

I couldn’t find an answer on google or the forums, but i fear I don’t know how to look it up as I’m not very familiar with the technical side of things yet.

Only what camera sees (it’s called backface culling) - unless you enable Two Sided. Materials are executed per visible pixel of a mesh. But beware shadow casting, because this works on entire geometry.