https://www.cnet.com/news/night-sight-camera-update-for-pixel-3-is-awesome/

"Night Sight is HDR+ on steroids," said Google engineer Marc Levoy in a previous CNET interview.  

Night Sight is available in the camera's menu option More, but if the camera senses a low-light scenario, a small dialog box will automatically pop up in the camera's viewfinder to suggest turning it on.