You can convert images into the .ico format by using an online converter. The Microsoft site also says that the maximum size an icon can be is 256x256. Here are some websites with free icons: ...

7. Convert optional images… If you are not satisfied with the existing icons, you can create your own. You can take an existing image and convert it to the ico format.

If the macOS desktop is looking a little boring, or is in need of a little more personalization than a change of background image, one solution could be to change how files, folders, and apps look.

You can add icons to your desktop in Windows 10 and more easily access the system apps or folders you regularly use. Here's how to do it.