How to open the wide angle of Canon 5D 4? I wonder how to use the wide angle in the camera? With 17-40 lens

The body of SLR camera is the guarantee of functional pixels, and the lens has wide angle, medium focus and telephoto. You don't need to open the wide angle 17-40 when taking pictures, just take off the lens cover and look out from the viewfinder. Turning the ring means zooming again, which means you are already using the lens. In short, the lens 50 is the head, and the wide angle less than 50 is the medium telephoto.