Nope, the geometry actually works out such that it doesn't matter your distance from the mirror, only how tall the mirror is and how high it's mounted.
A mirror that is as half as tall as your, mounted at head height, will show your ~~white~~ whole body regardless of how far away you are from it. TECHNICALLY, the bottom edge must be halfway between your eyes and feet, and the top edge must be halfway between your eyes and top of head.
In specific applications where it is useful to consider time as a 4th spacial dimension.
So if you're not talking about relativity, it's probably not.