To force a manual update of your address book in the desktop application, follow these standard steps: Microsoft Learn Offline address books in Exchange Online | Microsoft Learn
Downloading an (OAB) is the primary way to ensure you have access to your organization's contact lists even when working offline. By default, Microsoft Outlook updates this list every 24 hours, but users can manually trigger a download to immediately reflect recent changes or resolve synchronization issues. How to Download the Outlook Address Book Manually download outlook address book