- Unless things have changed, KB has said that it simply isn’t possible to add anchors in the text system used by Scrivener (i.e. for use inside Scrivener).
https://forum.literatureandlatte.com/t/bookmarks-with-a-single-document/6677/8
- For ebook or HTML output, you can add an anchor anywhere you want (i.e. for use outside Scrivener).
https://forum.literatureandlatte.com/t/help-with-html/38011/2
The project linked to above is for Scrivener 2. It still works in Scrivener 3.
- Another workaround explanation.
https://forum.literatureandlatte.com/t/bookmarks-with-a-single-document/6677/10