Samsung Email app controls light and dark mode

I found this little neat trick on my Samsung S7 phone. The Samsung Email app is controlling the phone's setting for light/dark mode. There is probably a setting for those on One UI with Android Pie or greater. But this is probably one way to set dark mode for older Samsung phones still on Android Oreo and below without installing additional apps.

After launching the app, tap menu on the top left then the gear button at the top of the menu. Tap "Display style" then choose "Always dark". 

This will force all other Samsung apps to go into dark mode. It will also affect every other app that uses Launch Screen for its loading splash screen such as the Google Play store, Maps and Drive apps.