Yes, it is possible. All you have to do is share the Virtual faxes module with the Tenant Administrator for that tenant.
This is done through the User Profiles, under Admin > Admin > User Profiles. There, you can modify the existing Tenant Administrator Profile, or create a new profile with the same options as the Tenant Administrator and adding the Virtual Faxes option.
Then, the Tenant administrator will be able to assign the virtual faxes to their tenants.