How i offer custom resolutions for user to choose?

For example, i want to make a square windowed game. But the default configuration only offer the native monitor resolution. So what should i do? i tried changing setting in Player Setting, no success.

@SunnyChow if you build your game and start the game the user can choose a resolution.


ingame this should help How can I change Screen Resolution and Quality Settings at runtime? - Questions & Answers - Unity Discussions