Just a note to make your post clearer. You should have posted 2 pics of the same set of comments. First pic showing a highlighted comment that can be expanded. With the 2nd pic showing th comment expanded fully showing full comment.
Facebook does 2 kinds of collapses. One shortens a post with “See More”
While the other collapses a series of comments that replied to a single comment.
Imho this is what caused some confusion with what you’re looking to achieve. 