The workspace retention cannot be extended beyond 730 days as of now. We are working on a solution to stream data to a colder storage. For now, the available option is to create a program (Azure functions, PowerShell, Logic Apps) that will read the date using the Log Analytics API and send it external storage.
Here in Western Australia we have the local "Office of Auditor General" reviewing local State Govt. departments and insisting that the policy is 3 years, I am assuming it is similar in most states and internationally this is likely to have other policies that are longer than the existing 2 years? We'll run with 2 Years (730 days) for now and make a determination on that later - can you advise what the best process is to formally request this so this request can be tracked? Should it be simply via a Support request?