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...
Source: https://www.gsmarena.com/the_pixel_4_will_have_a_dual_exposure_features_many_camera_samples_leak-news-39461.php
