Just like word documents are shit for papers and theses/dissertations it turns out. The formatting alone is a nightmare.

.gitattributes can invoke Word on windows to diff versions, and there are plenty of open source scripts that can do it if you don’t have a copy of Word (or Windows) lying around.

But Word is like shit for papers. Use LaTeX instead.

Unzip the docx with a pre-commit hook

(This is not a serious suggestion)

But better for LaTeX

Why on Earth would you curse yourself with MS Office anyway, especially if writing docs is your professional responsibility?

Why not use Git+Markdown+Pandoc, have your copy, data and layout separate?

I understand that a lot of istitutions/companies impose stylistic/technical requirements for docs and publications, - still doesn’t mean you gotta stay married to the worst tooling.