That’s not a hidden feature. That’s called reading the manualView attachment 257264
On the sportback you can set how far the boot lid opens using the two buttons above.
Open the boot
gently pull the lid down to the preferred height (if you pull to hard it will automatically close]
Press the two buttons above simultaneously until you hear a tone (about 5 - 10 secs)
next time you open the boot lid it will stop at the set position
you can also use the button on the right to lock the doors too