i'm trying to run with my own resolution so I inserted the resolution in the build settings. However, when I build it and run, there is no screen resolution option for the one I inserted. I want to build with screen by 9:16(common mobile resolution) but there are only ones like 10:9 or 16:9.
I search on Google and they told me to go to 'Edit'->'Player'->'Player Settings' but there is no 'Player' in mine. Can anyone tell me how to set up resolution?
9:16 and 16:9 aspect ratios are the same so you should be fine by using 16:9 and changing the screen orientation.
You can read more on the screen orientation here and you can set it in Player Settings if you build for mobile platforms. [Edit -> Project Settings -> Player is the right path.]
Screen orientation is platform specific and only appears when you build for mobile platforms (Android, IOS...). You can set it as you like or you can use AutoRotation value as well - in that case the device will determine how to display your game.