Any kind of text manipulation not possible on Facebook.
* Facebook does not allow any kind of text decoration (bold, italic, colors)
* Facebook does not allow any HTML and/or text formatting (different fonts, different size of the text, images in the middle of the text)
* Facebook does not allow titled links. (i.e you can’t make words “SNAP is Here” clickable). You can only post bare links that will become clickable.
All possible variations of Facebook posts are described here: https://www.nextscripts.com/snap-features/facebook-post-types/