A family of Microsoft word processing software products for creating web, email, and print documents.
The icons on the Windows taskbar are contained in the program files themselves, not in separate icon files.
What you can do is create a shortcut on the desktop that starts the program. In the Properties dialog that you can get from the right-click menu of the shortcut, there's a Change Icon button. When you click that, you get a dialog box where you can choose from any of the icons in the program file (there are usually several) or browse for an .ico file of your choice. The shortcut can be pinned to the taskbar instead of the program itself.
For instructions to create custom icons on the ribbon, see https://gregmaxey.com/word_tip_pages/ribbon_custom_icons.html