3rd Party (Non-Ring) Alert Tones for iOS

I'm switching from android to apple and appreciated a deep library of alert/motion tones on Android that I can't find on Apple. When adjusting the alert tone for motion or a doorbell ring it only shows the default set of Ring 1st party tones (windchimes, etc).

How can I add custom tones? For example, I use a car honk sound to let me know someone's on the driveway, etc.