(I'm not on a Windows computer right now so I can't test it.)
Very commonly, Windows icons are stored directly in Windows' DLL or EXE files.
This library can extract icons from DLLs and EXEs:
Extract icons from EXE or DLL files[
^]
The executable of the Settings app is definitely worth a try, but the icons could well be stored as part of another file - or not at all stored in this way. And because we don't have access to the source code, we can't just figure it out.