Setting screen ratio not work correctly

Hi. I want to fix screen aspect ratio 16:9. I used to Display.SetRenderingResolution in older version of Unity, but it is not work now(2017.4.6f1). It shows horizontally stretched screen in 2960 x 1440(galaxy s8). I tried Screen.SetResolution but it was same as SetRenderingResolution with fullscreen option true, and it shows software keys in fullscreen false. And I tried androidmanifest android:windowSoftInputMode="stateHidden" option, it shows hidden in start, but it appears when setting screen resolution. What I want is 16:9 display with fixed aspect ratio, and the empty spaces are black without software keys. How can I do this?