I think hdmi's link will be worth having a look at.
There have been several discussions about changing shell32.dll.mun & imageres32.dll.mun here & in TenForums.
- It was in Windows 10 that the change from imageres32.dll etc to imageres32.dll.mun etc started.
- Whilst icons appear to be in imageres32.dll etc, they are actually in imageres32.dll.mun etc.
- The .mun files are in C:\Windows\SystemResources
- Things did keep getting confused in TenForums discussions because, as we eventually recognised, the changeover to mun files was being done gradually in successive Windows updates so we were not all looking at the same things. This might also be the case in Windows 11 for all I know.
IconViewer - Extract Icon from File in Windows - TenForumsTutorials
Custom Icons - ElevenForum
Reg file to easily change most Windows icons - TenForums
Some people referred to the tool
Customizer god which I think has been mentioned in this thread as well.
Icon overlays explanation 1 - RickC post #5 - TenForums
Icon overlays explanation 2 - RickC post #8 - TenForums
Change Drive Icon - TenForumsTutorials
And see
non-icon icons [Whackbag #3] - TenForums
How do I change the icon for the Windows 10 calculator app - TenForums
All the best,
Denis