We can also use the Google Docs API Advanced Service to retrieve text data from a Google Doc with Apps Script or indeed, with any other programming language. This returns a JSON Object for the current doc.

This tutorial is 4 of 4 approaches to programmatically extracting text from a Google Doc. There is no one complete approach, unfortunately, but each approach comes with its pros and cons. Check out the written tutorial for more details @WorkspaceDevs
https://youtu.be/BEtj42ufWhU