A family of Microsoft word processing software products for creating web, email, and print documents.
To have the document display fully within the Word window, go to the View tab of the Ribbon and choose Page Width from the Zoom settings.
There is View > Focus if you want to experiment with that, but the document doesn't fill the window the same was as with Zoom > Page Width.
You can use a macro to automatically size the widow to full screen when the document opens.