You will be required to install the Substratum Theme Engine and have root access OR the Andromeda add-on, if you want to apply this theme:
An overlay that enables Always On Display modes for devices running Android 8.1 Oreo and above.
For more details on this modification:
Known Issues (as of 12/09/2017):
• Waking the screen using the power button or double-tap can be wonky and will get you stuck on a black screen. Can get yourself out the black screen by the locking the screen and using the fingerprint to unlock the device.
This theme is 100% open-source
Contact for support, suggestions, and whatnot:
• Substratum Telegram: t.me/Substratum
• Telegram Group: t.me/SaiThemes
• Telegram PM: t.me/BakaBakaBaka