After application Keepthe dark theme and got the calendar from Google.
Support dark themes are available in Google Calendar version 6.0.36. You can download it from Google Play store or manually installing the APK. To activate dark mode, you must go to app settings, section “General”, and there find the item “Subject” (Settings – General – Theme). You can choose to force a light or dark theme, and configure automatic switching depending on the power saving mode.
By the way, when you switch themes updated interface is not only the application but also a widget for your desktop.