How to Turn on Dark Mode in Microsoft Word 

Here is how to turn on dark mode in Microsoft Word.
After you open Microsoft Word: Click on the File menu in the top left corner of the window. This opens the backstage view, where you can manage Word's global settings.
Access Options: Scroll down to the bottom of the list on the left side and select Options. This opens the Word Options dialog box.
Select General: In the Word Options dialog, look for the General category in the list on the left side of the window.
Office Theme: Within the General options, find the section labeled Personalize your copy of Microsoft Office. Look for a setting named Office Theme or simply Theme.
Choose Dark Mode: Click on the dropdown menu next to Office Theme and select Black or Dark Gray (depending on your version of Word, the exact naming might vary, but Black is typically the darkest theme available).
Confirm and Apply: Click OK to apply the changes. Microsoft Word's interface should now switch to the selected dark mode, affecting the ribbon, toolbars, and some background elements.