Also called "boot touch edge changes", this is a simple flexing drill - basically just touch your boots when the skis are flat, but it may be hard on the body, especially your back - make sure you Warmup and stretch first.
On a blue run, touch your boots in transition. So, as the outside ski is long at the apex and you decide to end the turn, flex that leg to make both legs short and touch both boots as they become flat on snow.
Touch the sides of the boots, not the tips. The idea is to get you to flex the legs more and more, not to hunch forward from the hips. Do make sure you don't end up too far back on the skis either - so you could think of it as trying to touch your little toes rather.
If you have trouble with this, work your way to it by touching the sides of the knees first and then get lower and lower.
Remember to focus on flexing the long outside leg and having both bent/short legs in the transition:
Again, this may be challenging, but high-performance skiing does require more movement. Some dryland training to increase your flexibility and mobility and back strength are more than welcome.
This is a quintessential drill to develop the range of movement for flexing. Another version is to touch your boots all the time - this is for flexing awareness and workout: