This feature will be available in Hue Essentials update 1.31.0 for Android and 1.22.0 for iOS.
Access the new feature by going to the Devices tab at the bottom, and select your light.
For more information see: Switch off a light/plug automatically 10 minutes after it turns on
The update should be available within a few days/weeks. The update will be rolled out to beta first and some platforms may get it earlier than others: If you would like to join the beta, see the following: Join the beta - Try new features before they are officially released