Hello @Sanket ,
it should be in the SAS RTDM 6.6 documentation https://documentation.sas.com/?activeCdc=rdmcdc&cdcId=cicdc&cdcVersion=6.6&docsetId=rdmug&docsetTarg...
I would expect to find the documentation in the Administration Guide, you will need the access key. If you have the license for it, SAS Technical Support should be able to provide it to you, if you don't have it yet.
If it is an upgrade in place, it should not be very different from other upgrades in place, considering the particularities, of course, for 6.5 to 6.6.
Best regards,
Juan