Render texture on slim plane

I'm working on a project where I'm using a render texture to show the view from a camera. I've placed the render texture on a plane but since the plane is very slim the view gets "squished" making it very distorted. Is there a way to keep the render texture the original size and instead choose the part I want to show? Something like this: I started learning Unity last week so If you could give a code example or point me to a tutorial that shows how to do it I would really appreciate it.