Mackenzie Foy was 10 in The Twilight Saga: Breaking Dawn - Part 1 when she played the character 'Renesmee Cullen'.
That was over 12 years ago in 2011.
This was her first recorded movie acting credit (although may not technically be her first actual acting role).
Today she is 23, and has starred in 14 movies in total, 12 of those since The Twilight Saga: Breaking Dawn - Part 1 was released.
In The Twilight Saga: Breaking Dawn - Part 1, I think Mackenzie Foy looks: