Can I format a book in Microsoft Word?
Updated
You can, but it fights you: Word can't do mirrored gutters that grow with page count, recto-only chapter openers, suppressed running heads on openers, or reliable font embedding in exported PDFs. Authors who try usually spend days and still fail KDP preflight. Write in Word; typeset elsewhere.
Word is a word processor, not a page-composition engine. Its section breaks, header states ('different first page' per section), and mirrored-margin settings can approximate a book — fragile at best, and one edit reflows everything.
The deeper issues are typographic: no real widow/orphan+hyphenation quality control, no drop-cap system worth using, no gutter-by-page-count math.
The efficient workflow is the industry's: draft and revise in Word, then hand the finished .docx to a typesetting tool that outputs print-grade PDF and EPUB.