Keep Coding

Assume that I have a boolean that indicates whether the app is launched for the very first time or not (so I can show some guides for the first time)
I encapsulated that boolean into a model class (may be called AppContext)
class AppContext {
var isFirstLaunch: Bool
var otherAppScopeVar: Int
// ...
}
Can I test this kind of things?

you shouldn't!
you should only test your application behavior in those two scenarios.
you need to execute your application after injecting that data with its two different states in order to test both scenarios.