Kiernan Shipka was 16 in The Blackcoat's Daughter when she played the character 'Kat'.
That was over 7 years ago in 2017.
Today she is 24, and has starred in 23 movies in total, 3 of those since The Blackcoat's Daughter was released.
In The Blackcoat's Daughter, I think Kiernan Shipka looks: