I've done it using VCDS.
In Module 09 Central Electrics -> Adaptions
Channel was:
IDE08542-ENG116658-Access control 2-Funk Spiegelanklappen: Not Active
IDE08542-ENG116665-Access control 2-Funk Spiegelanklappung Modus: By convenience operation via remote control key
IDE08542-ENG116660-Access control 2-Menuesteurung Funk Spiegel anklappen: Not Active
IDE08542-ENG125658-Access control 2-Profilfunktion fur Anklappung der Aussenspiegel: Not Active
IDE08542-ENG126612-Access control 2-Spiegelanklappung geschwindigkeitsabhangig: Active
Channel changed to:
IDE08542-ENG116658-Access control 2-Funk Spiegelanklappen: Active
IDE08542-ENG116665-Access control 2-Funk Spiegelanklappung Modus: By look command via remote control key
IDE08542-ENG116660-Access control 2-Menuesteurung Funk Spiegel anklappen: Active
IDE08542-ENG125658-Access control 2-Profilfunktion fur Anklappung der Aussenspiegel: Active
IDE08542-ENG126612-Access control 2-Spiegelanklappung geschwindigkeitsabhangig: Active
Now in the car, go to Car Settings -> Mirrors and Wipers.
Previously this menu had been curiously named as despite the name, it only had options for wipers with nothing at all to do with mirrors.
But now you'll have a new option of "Mirrors - Fold away after parking". The menu item should already be ticked from the VCDS changes.
Mirrors behave exactly as you'd expect - fold away when locking, and unfold when starting the ignition.