Apple has not really changed the notification tones on the iPhone since iOS 7. How come you hear strange pings, plunks and dots from your iOS device? No, it's not an app you've downloaded (although third-party apps may have their own notification sounds). Instead, it is likely that you have upgraded your iPhone to iOS 13.
The latest iOS update includes over 200 new features, not to mention over 20 additional changes that iOS 13.1 brings to the table. These changes include a new sound suite for Tapback, an iMessage feature introduced in iOS 10. If you do not know Tapback by name, you know it from experience – these are reaction options that are not available in Love, Likes, Like, Laugh, Emphasize, and Ask.
In the past, tapback notifications used the same notification tone as your other messages, and would even arrive silently when in chats. With iOS 13, however, every tapback has its own unique alarm tone. What you hear are the three pings of someone "loving" your message, "pinging" a "question" response, or one of the other four new reaction alerts. Apple uses these sounds in both chat and iOS, so you can quickly distinguish between a real message and a simple tapback response.
If you're not a fan of these new sounds, you're out of luck. Of course, Apple does not provide a way to customize the warning sounds for Tapback, nor does it offer any option to completely mute them. If you do not want to hear tapback, you must turn off the tones for all message notifications. This is a bit much if you ask me.
A less drastic measure? Silence your iPhone with the mute.