Is there a way to “lock in” pages of a doc so they do not … – Google Help

So in terms of locking pages, there really isn’t a perfect solution at this time. Please share your concerns about this directly with the Docs team by opening a Docs document and going to Help > Help Docs improve. The team is unable to respond to individual users, but they do review all feedback sent to them and use it to improve the app over time.

https://support.google.com/docs/thread/183247022/is-there-a-way-to-lock-in-pages-of-a-doc-so-they-do-not-change?hl=en