Perspective

Perspective is the relative change of size of subjects at different distances to the camera.

Perspective changes with the distance to the subject. Changing the focal length does not change the perspective. To change only the perspective you must change both the distance to the subject and the focal length so the subject is framed identically from a different distance.

The difference in apparent size of the two subjects will be come smaller as the camera moves further away.

At extremely long distances the perspective becomes completely flat and there is little or no difference of apparent size between the subjects.