The new Chrome OS is now available for CR-48. If you are using Chromebook CR48 you can use the new UI and new features by using the Dev Channel instead of Stable Channel.
Today Google upated the Dev channel to 20.0.1105.0 (Platform version: 2153.0.0) for Chromebooks (Acer AC700, Samsung Series 5, and Cr-48). This release contains functional, security and stability improvement.
One of the most notable features of the this update is the brand new UI of Chrome OS which looks like c 'traditional' desktop. You can read the complete review of the new UI of Google Chrome OS here.