The developments are long and not always uniform. It is at these times that we see design inconsistencies. Fortunately, most of them are temporary. Now, after we start applying a dark theme in some Office apps like Outlook or OneNote, we’ll move on to Word soon.
Word will release its dark theme soon and you can already see the result
As Florian B reported, Microsoft is currently working on full support for dark themes for the desktop. This time for the popular text editor, Word. This means that once the feature is available to the public, you can apply the dark theme throughout the app.
The option to enable dark theme is already present in Office, but enabling it applies the dark theme to certain sections of Office applications. For example, enabling the option will apply the dark theme to the ribbon and other areas of Word. But with this new feature, users will be able to apply the dark theme in the document area, status bar, and pretty much anywhere.
The feature appears to be in the development phase, which means we may have to wait some time before Microsoft makes it available to the public. But from Florian B’s tweet, it looks like Office Insiders will soon get full dark mode support on the Word desktop before everyone else.