Question
For some reason, the icons are much bigger on one PC compared with another. How to adjust the size of desktop icons?
Answer
Reduce the display scaling and you will see a smaller icon.
You can also press Control + mouse scroll wheel (if exisiting) while at the desktop background to change icon sizes. Use the same method to get your icons back to normal.
Right-click an empty desktop space, select the View option from the context menu, then click on the Small icons option. Sometimes the Medium icons and Large icons settings don’t work because the icon file doesn’t have multiple icons with large enough pixel sizes, but there should always be an icon that works with the Small icons setting.
Reference
Windows Support > View display settings in Windows