[Nightblood.]

Thirteen - A girl self harms and does drugs
Short Term 12 - Two of the characters self harm, it's not the biggest focus but plays a large role
Wristcutters: a love story - basically, people that commit suicide all go to the same place. it has some self harm but isn't the main focus
Girl, Interrupted - has some self harm, but focuses more on life in hospital

I have some more but they're mostly movies in which it's either briefly mentioned/shown, or is a lesser plot line. I also have a few that are more about mental health/suicide and less about self harm. There really aren't TOO many movies explicitly about self harm like painful secrets/secret cutting was.