Millie Bobby Brown was 14 in Godzilla: King of the Monsters when she played the character 'Madison Russell'.
That was over 5 years ago in 2019.
This was her first recorded movie acting credit (although may not technically be her first actual acting role).
Today she is 20, and has starred in 9 movies in total, 3 of those since Godzilla: King of the Monsters was released.
In Godzilla: King of the Monsters, I think Millie Bobby Brown looks: