Can I get a copies of previous reconciliation reports (maybe last 3 mos) for a checking account?

Are you asking for monthly bank statements from prior months? Those are available for downloading and printing from the bank's website.

In Quicken there's a Reconciliation Report which can be generated manually after you complete a Reconciliation process at the end of the month. This report is also available from the Reports Menu / Banking / Reconciliation. But unless this report is generated immediately after completion of a Reconciliation and before making any transaction changes, additions or deletions, the report is more or less meaningless when created at any other point in time.

Please note that Quicken does not maintain a history of the Reconciliation Report's data.
In order to retain such a history, one would have to "print" this report to a PDF file and save it for later.