While mentioning distraction free alternatives, even Word has a full screen "Focus Mode", if that is the tool you have available or need to use for whatever reason.
Another useful tip: Word's Focus Mode, like some of the ones mentioned, goes to a Full Screen window. In Windows 10 you can set "Focus Assist" settings that will turn off all notifications that Windows is aware of and things like that whenever you are using a full screen application. (I believe that particular Focus Assist option is actually the default now, but it's easy to double check.)
Another useful tip: Word's Focus Mode, like some of the ones mentioned, goes to a Full Screen window. In Windows 10 you can set "Focus Assist" settings that will turn off all notifications that Windows is aware of and things like that whenever you are using a full screen application. (I believe that particular Focus Assist option is actually the default now, but it's easy to double check.)