A 13 year old girl started in Septenber 2019 in my training groups.
The x-ray of her spine shows on the left in the beginning of 2019. The middle picture is from December 2019 and the picture of the right is from 24 of June 2020.
For sure, a younger person is able to change quicker the posture of the body.
But the most importent is consistent and conscious training on all levels.