Incident records are archived 18 months after they are closed and destroyed 18 months after archiving (total of 3 years after closure). Change requests and requests, while not explicitly defined with the same 3-year retention period, are generally retained within the ServiceNow instance until they are explicitly removed by users or administrators.

You can build archiving rules to manage data on your tables.
https://www.servicenow.com/docs/bundle/yokohama-platform-administration/page/administer/database-rot...

Please accept my solution if it works for you and thumps up.