BepInEx.ConfigurationManager

https://github.com/BepInEx/BepInEx.ConfigurationManager

An easy way to let user configure how a plugin behaves without the need to make your own GUI. The user can change any of the settings you expose, even keyboard shortcuts.

The configuration manager can be accessed in-game by pressing the hotkey (by default F1). Hover over the setting names to see their descriptions, if any.