Limit available app languages

I have my app localized for many languages, but I'd like to limit the available app languages to only a subset of those, because the content is not ready for all of them.

I don't want to delete localization files, because they contain some useful translations that I will use in the future.

The only thing I was able to find and try out is this piece of code:

class AppDelegate: NSObject, UIApplicationDelegate {
  func application(
    _ application: UIApplication,
    didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
  ) -> Bool {
     
    UserDefaults.standard.set(["Base", "pl", "de", "ru"], forKey: "AppleLanguages")
    UserDefaults.standard.synchronize()
     
    ApplicationDelegate.shared.application(
      application,
      didFinishLaunchingWithOptions: launchOptions
    )
    return true
  }
}

but unfortunately it does not work. When I launch Settings of my app, I can still choose from about 20-30 languages that I have already some translations for.