It's a question that has a rather long set of details!
First, a picture has a true size measured in pixels, not inches.
A scanned picture also has an original size measured in inches, centimeters,
A printer has multiple resolutions based upon dots per inch. More than one
dot may be used to represent a picture pixel.
Printers vary from model to model and from one mode to another in how many
dots per pixel are used.
Picture editors that have printing and layout capability generally allow the
user to scale and position a picture on the paper size to be printed.
Some will also allow the picture to be scaled to fit in a standard photo
Using my Win 7 system with an Epson Workforce 600 printer with MS Picture
I can adjust the print size within the advanced printer properties selection
from MS picture Viewer.
The capability to completely adjust size is locked out for some reason.