Size and visibility are separate questions
A face-on disk of diameter D at distance d subtends 2 atan(D/2d). A distant object becomes harder to resolve as that angle decreases. Better optics can recover detail that was present but unresolved.
Occlusion removes a path
If the lower part of a target lies below the limiting sight line, no direct straight ray from it reaches the observer. Enlarging the remaining image does not create that missing path. Refraction can alter the path, which is why weather and height belong in a long-distance record.
A controlled zoom comparison
Keep the camera at one measured height, use a target with identifiable levels and retain full frames. Compare the highest and lowest visible features at several focal lengths. Repeat from a greater height to separate resolution changes from sight-line changes.