As we saw in the leaked specs list, the Pixel 4 will have a new image processing chip – the Pixel Neural Core (the previous generation hardware is called Visual Core). There will be changes to the camera app as well, including a new Dual Exposure feature.
This mode will allow you to separately control the highlights and shadows in the photo. So, it’s sort of line manual HDR mode (HDR takes a short exposure for the highlights and a long one for the shadows and then merges the two images).
Here’s short video showing the dual slider in action:
And here are some camera samples…