Block File Sharing in Teams

Hi,

As referred to in the previous link you can control external sharing on SharePoint and OneDrive at a tenant level or at a site level (with permissions), or you can apply Data Loss Prevention policies on content within SharePoint/OneDrive from the Office 365 Security and Compliance Centre

Here are the links

https://docs.microsoft.com/en-us/sharepoint/turn-external-sharing-on-or-off
https://docs.microsoft.com/en-us/microsoft-365/compliance/data-loss-prevention-policies

Best, Chris