lineageos – Where’s the Android 16’s ‘expanded’ option for dark theme?

Google has highlighted this feature in their release notes:

We’ve heard how frustrating it is to switch from a dark app to a glaring light one. With the new expanded option for dark theme in today’s Android 16 release, your phone will now automatically darken most of the apps on your device, even those that don’t have their own native dark theme. This creates a more consistent and comfortable viewing experience, especially for people with low vision or light sensitivity.

I was eager to try out the feature for my near-mandatory banking app which only supports a basic light theme. I contacted the support on the accessibility grounds months ago and received no reply.

There’s no such option for the dark theme on my LineageOS 23 / Android 16 device. Searching for expanded also returns no results.