Do you not agree that - OOC, distance to subject being equal for both cameras - the subject will be bigger in the frame in the image from the 7D Mk II?
Ian's right. Which FF and crop camera is involved in the test is utterly irrelevant.
Sorry, but you and Ian are wrong.
With the distance to the subject being equal and the same focal length used on both cameras, the subject will fill a larger
proportion of the frame on the 7DII than on the 5DsR...a larger proportion of a smaller frame. If you then crop the 5DsR image down to APS-C size, the resulting image will be identical to that from the 7DII, i.e. a 20 MP image with the subject filling the exact same proportion of the frame (except the 5DsR image will be a bit sharper due to the lack of an AA filter).
Broadly speaking, the concept that appears to be eluding you is ‘pixels on duck’. Comparing the output from a 7DII to my 1DX, the crop camera puts more pixels on a subject of a given size. But comparing the output from a 7DII to the output of a 5DsR, the number of pixels on a same-sized subject are identical, meaning the output can be made identical by simply cropping the full frame image.
Certainly the subject will appear larger in the viewfinder of the 7DII, which has implications for composing and focusing. However, Ian specifically mentioned output.
I honestly thought you understood these concepts better. I guess it goes to show that no matter how skilled a photographer, technical understanding does not always match.