User Configuration > Administrative Templates > Microsoft Word 2016 > File Tab > Check Accessibility
User
HKCU\software\policies\microsoft\office\16.0\word\accchecker
This policy setting prevents the Accessibility Checker from checking to ensure that long documents have used styles to define content structure. If you enable this policy setting, the Accessibility Checker will be prevented from checking to ensure that long documents have used styles to define content structure. If you disable or do not configure this policy setting, documents will be checked for style usage and any issues will appear in the Accessibility Checker.