Google always uses a single camera set up on the back in Pixel Line Phone. But to compete with other brand phones, Google might use a Dual Camera set up in Pixel 4 which is first in the line.
Now you wondering will Google use an Ultra-Wide Lens or a Telephoto Lens? To answer this question, I answered it with Yes, they use both and even a Normal Shooter with them. Google will use either a Triple Camera Setup or Dual Camera, that’s not confirmed.
But still, there are rumors coming up that Google will use a Telephoto lens instead of Ultra-wide lens which is a heartbreak issue of Ultra-Wide lens fans.
The Developers of Google Camera App have already started to work to support Pixel 4. There will also be a front IR Sensor in the new Pixel 4 which will enable the Face Authentication feature in Android Q.