Zooming WebCamTexture?!?

Hi, I am masking a RawImage with a shader. A WebCamTexture is set as the main texture of the material of the RawImage. This is the result:

The problem is that I want my face to fill the circle, and I want to be able to save it like that. So my very texture must be "zoomed" or distorted somehow. I did some research but I still have no idea how to do this. Or maybe better, is there eventually a shader for a 2d game that can mask a image and add a distortion/ zoom too?

Thanks.