If you need to grant a user or group standing access to users' personal sites, you may want to consider assigning a secondary site collection admin. To set a secondary site collection owner globally, follow these steps:
- Launch the User Profile Service application from the classic SharePoint admin page.
- Under My Site Settings, select Setup My Sites.
- Scroll down to My Site Secondary Admin.
- Ensure the Enable My Site secondary admin box is selected. Then, add a username or security group through the user picker:
- Scroll to the bottom of the page and click OK.
This change only affects OneDrive for Business sites being provisioned going forward. It does not impact existing sites.
For more detailed information on the User Profile service, such as how properties are mapped, the Azure Active Directory import timer job, or Service Level Agreement (SLA) notes, see https://support.office.com/en-ie/article/information-about-user-profile-synchronization-in-sharepoint-online-177eb196-5887-43c9-84c3-b98a43d35129.