I was wondering about that too, it seems like it's partly in this test report:

https://www.dxomark.com/wp-content/uploads/2025/06/AppleiPho...

and then more context, especially for the less objective categories, in this test protocol description:

https://www.dxomark.com/smartphone-camera-image-quality-test...

It was a little annoying to find (About Us > How We Test) but not awful I suppose.