A Google app called Sounds recently appeared on the Play Store. It appears to be an app for Pixel phones that includes sound settings, letting you choose sounds, ringtones, and more. There appear to be visualizations for each ringtone, too, but the folks at Android Police note that there are no new visualizations, suggesting that perhaps the app was discovered early and isn't at its final version right now.
Also of note is that while the Sounds app is live in the Play Store, it's not showing up for everyone right now. It's possible that you need a Pixel phone to access it right now.
We've seen Google spin out some of its apps into the Play Store before for easier updating, and so it's possible that that's what's happening with this Sounds app. When it officially launches, this app may allow Google to easily give Pixel owners some new ringtones and visualizations.
Google Pixel owners, are you seeing this Sounds app in the Play Store?