Click here for a TechRepublic article from April 2021 called " How to purge entries from your Chromebook clipboard" that is easy and useful for the security minded.
Click here for a HowToGeek article from March 2021 about using the Chromebook facility.
Click here for a 9to5google article from July 2020 about an upcoming feature that will hopefully make it's way to the Chrome browser soon.