Office for macOS: Word document opens in a tiny window

I'm using Office for Mac version 16.25 (2019) on a Mac macOS High Sierra. Whenever I open a Word document or create a new file, it opens in a tiny window, which occupies less than 25% of the screen size. I can resize it, which is a pain, but if I close and reopen, the window again opens small.

I've found answers that involve editing the default template (.dot) file. This has no effect. What used to be easy now appears impossible.

How do I resolve this issue?

1. Close all Word documents.

2. Open a blank Word document.

3. Resize the window to the preferred size.

4. Finally quit Word by using Menu bar command Word → Quit Word or using the keyboard shortcut Command + Q.

Next time when you open your Word document it should remain in the previously set window size.