For users on the Basic and Team plan, creating a thread of comments to enhance collaboration is possible. Sharing the document via the editable link can then allow users on the free or Solo plan to comment as well.
Highlight the text you'd like to comment on, and click the comment icon.
Write your comment and click the green "Send" button.
Click the highlighted text to open a comment thread. Click the three-dot icon to delete or edit your comment, or resolve the thread.