From the Centos list:
Wed 27/01/2021 13:20
From Anton

To:
[log in to unmask]
Centos-6 compatible packages are available from the official sudo
webpage. It's a later version of sudo and I'm not sure if that will
cause problems. I've tried installing it and so-far so-good.
https://www.sudo.ws/download.html
# End quote.
It has worked on the small number of SL6 systems I have.
Rhys