How to make device vibrate more intense?

Now I have an extension to make the device vibrate from anywhere in the app:

extension UIDevice {    static func vibrate(style: UINotificationFeedbackGenerator.FeedbackType) {        guard CHHapticEngine.capabilitiesForHardware().supportsHaptics else {            AudioServicesPlaySystemSound(kSystemSoundID_Vibrate)            return        }        let generator = UINotificationFeedbackGenerator()        generator.notificationOccurred(style)    }}

The problem is with the devices, that uses haptics. Now I am using style as warningbut the device vibration is very weak, not even noticeable. Is there another way to make the device vibrate 2 times, or more intense?

I have tried different vibration styles in code, but vibration is still very weak.