Ok, I can see the point, but it’s not usually what people mean when they can see their whole body. In that example, you’re looking down or looking up. You never see your whole body at the same time. For your whole body to be entirely in your field of view, it absolutely does matter how close or far you are from the mirror. You can test it by going closer and further to any mirror.
Ok, visualize it like this:
Draw yourself, with a small mirror at head height, a meter away. Draw your reflection at the same distance from the mirror on the other side.
Now do that again, but place the mirror 10 times further. Then draw lines from your eye, to the edge of the mirror, and to the reflection.
You’ll reach the same point on your reflection.
Edit: or let the BBC do it for you; https://www.bbc.co.uk/bang/images/dallas_mirror_diagram_large.gif
Ok, I can see the point, but it’s not usually what people mean when they can see their whole body. In that example, you’re looking down or looking up. You never see your whole body at the same time. For your whole body to be entirely in your field of view, it absolutely does matter how close or far you are from the mirror. You can test it by going closer and further to any mirror.
… buddy, have you tried it? Get up, walk to a mirror and test it. You’ll find that the picture shows you what happens