Google seems to be going with a massive camera module, which contains two cameras on the rear along with a third sensor that could possibly be a ToF sensor.

Google officially reveals what Pixel 4 will look like
Atom Tech Shorts Friday, June 14, 2019 - 11:07

After several leaks, renders and iterations of what the next Google Pixel may look like, Google has itself gone ahead and officially shared a render of its device to be launched in October. The company has posted an image of the upcoming Google Pixel 4 on its official Twitter handle. The image is of the rear of the phone and an accompanying message says "Well, since there seems to be some interest, here you go! Wait 'til you see what it can do". Observers say some leaked renders would have prompted the company to take this step.

The highlight of the phone from this image is the camera sections. The dual camera setup in the rear is clearly visible and another sensor can be seen which can only be imagined to be a Time of Flight camera. Now, the previous models of the Google Pixel phones did amazingly well with their photography department with just a single camera. You can imagine what a dual camera with the ToF lens could do to the Google Pixel 4. May be the message in the tweet referred to above had a message in it. An LED flash can also be noticed on the rear panel.

Apart from these, some design aspects too stand indicated. One is the back panel appears to be made of a single material, the render showing a black colour in a consistent shade throughout. The official render of the Google Pixel 4 shows the physical volume rocker and power buttons are very much part of the design.

There are other leaks and rumours suggesting that the front will also come with a dual camera setup with the lenses lodged in the notch or punch hole.  

Many of these may still change since there are four good months before the launch of Google Pixel 4.