Let's take the following example document:
How can I create an anchor link for the heading "How to boost sales" to share this document position with another user?
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Sign up to join this communityYou can create a bookmark.
Place the cursor where you want to link to, and select Insert → Bookmark from the menu.
Click the Link item in the popup menu:
The browser location bar now shows the URL to the bookmark, which you can forward to other users (that have access to the document, of course).
Beyond adding bookmarks, every document heading (Format > Paragraph Styles) automatically makes an anchor. You can see the URL change as you navigate through the different headings.