Facebook will not try to show your suicidal teen stuff that could help them. Facebook will only show your suicidal teen things that keep your suicidal teen doomscrolling.
Facebook WILL put a small textbox of "Here's the suicide hotline" and then overshadow it with a huge ad for "You aren't pretty enough, buy this body deodorant" that autoplays and includes sound and can take over part of your screen.
Facebook WILL show your suicidal teen stuff that makes them really angry. They do this on purpose. They do this knowingly. That's what "optimizing for engagement" means
My favorite part: just-in-time ad delivery to your suicidal teen for products they might need