Explanation:

Users must be able to manually select that email messages are sent encrypted. The encryption will use Office
365 Message Encryption (OME) v2. Any email containing an attachment that has the Fabrikam Confidential sensitivity label applied must be encrypted automatically by using OME.
Reference:
https://docs.microsoft.com/en-us/microsoft-365/compliance/ome-sensitive-info-types?view=o365-worldwide