The container management settings of sensitivity labels can now manage the external sharing capability of SharePoint Online team sites. The same settings as available in the SharePoint admin center or PowerShell can be applied through a label. Caching means that new settings in a label might not be picked up by SharePoint Online for up to 24 hours.
https://office365itpros.com/2020/12/09/sensitivity-labels-control-external-sharing-sharepoint-online...
