You can create & add a document outline in Google Docs using this guide. Difference between Table of contents & Document Outline explained.

To automatically create a table of contents, click Insert > Table of contents in the top menu. Creating a manual table of contents involves structuring it to match the document outline and linking ...

Adding a summary to a Google Docs document is useful for both the author and the reader. For the reader, it gives them a brief overview of the document without having to read the whole thing. It ...