I have an image of a galloping horse and have cut it out in silver. I need to have an image a little larger than the original to make it look like a shadow around the whole horse. When I try to resize it in Inkscape it does not resize in proportion even though I have the image locked. Tried with image unlocked also a little better but not exact. Can someone help please.

Work with us! Give us a little more info, a screenshot, a file, a picture ... only the moderators here are psychic. And that's only on Tuesdays.

i think what OP is asking for is a dynamic offset

although mostly (drop)shadows are just black and blurred duplicates of the object

Certainly it's not yet Tuesday.

You write image and locked -do you mean paths, and locked proportions?
If so, it should work, which means we would need to take a look on a visual of your file/screenshot of the problem.
Or provide us a more precise description.