There's no doubt that Samsung'sOne UI is the best user interface in Samsung smartphones ever, and one of the cool features is its 'Night Mode' which changes the system level interface into a new dark theme and makes the mobile navigation easy in the dark environment.
But other than its Night Mode, there are new free 'High Contrast Dark Themes' that you may wanna give a try. These high contrast themes add a new layer of colors and icons to your touch controls in the theme, without even applying the 'Night Mode'.
If you have got the One UI installed on your Galaxy S9 or Note 9, you can download these themes by simply visiting the Samsung Theme store.
Check the screenshots below.