Is the selfie camera less quality than the similar wide front facing camera?

While it is 12 MP, the number of pixels is only one factor in image quality. The lens is even more important than the number of megapixels. The Selfie camera does not appear to have as good a lens as the back cameras, and it is an f/2.2 aperture, compared to f/1.5 on the back standard focus camera. But it’s probably not enough difference to notice on other than very critical images.

The selfie camera or True Depth is the front facing camera.

The other three cameras are rear facing

Most cameras have lesser resolution Front Facing camera but the 13 Pro Max appears to have all cameras 12MPx

https://www.apple.com/uk/iphone-13-pro/specs/