This theme is for LG V20 G5 Oreo only. If your device has been updated to Android 9. Please install the theme for UX8. You can visit my website for more information. I have tried to bring up the theme with dark background notifications, but with 3rd party applications many applications do not support so there is a possibility that dark text may appear on the dark background.
The app has been originally designed by WSTeams and it refers to the Personalization category. MIUI Dark Theme LG V20 G5 Oreo was downloaded and set up by over 1K users and its latest stable update was on Apr 23, 2019. This application was rated 4.4 on Google Play.