The function was expected.
It can't be hidden that one of the biggest new features introduced with Android 10 is the system-wide dark theme. Fashion for the so-called dark mode seems to have no end, which motivates developers to implement "darkness" in most of their applications. A nice touch would also be the ability to manage this dark theme. Not every consumer wants to have it activated all the time.
As we can read in the commentary on Google Issue Tracker, the title function may already appear in Android 11 now known as "R". If this is true – users will be given the option to choose specific hours when their applications should switch from light to dark theme. Admittedly, this possibility could prove extremely useful.
However, we will wait for the next version of Android. The specific release date of the new version of the software has not yet been given, but it is said that beta testing of the system will start in March 2020. It remains to wait for official confirmation from Google.