Google Docs is the top online document editor, hands down. If you're working on document, you can quickly create an outline in Google Docs.

Google Docs is available for computers and mobile devices, and you can create outlines on both platforms. The computer version is accessible via browsers and gives you an expansive view of its ...

Without adding headings, you can't create an outline or table of contents in Google Docs. Headings let you easily jump through different sections or move straight to the summary in long documents.

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