FedEx One Rate supports these services:

To use FedEx One Rate, you must enable One Rate services and One Rate container types in D365 F&SCM.

Limitations

Shipping Carriers

Transportation management > Setup > Carriers > Shipping carriers

Make sure the desired FedEx One Rate services are enabled in Supply Chain Cloud. (See Step 4—Configure Carrier Services—of Getting Started with Ship for more information.)
Add FedEx as a shipping carrier if not already set up. (See Shipping Carrier Setup for more information.)
Select the desired service from the prepopulated Ship Carrier Service Code drop-down list in the Services section.
The External code is automatically generated. This aligns your Finance and Supply Chain Management setup with the carriers and services in Supply Chain Cloud.

Container Types

Warehouse management > Setup > Containers > Container types

Make sure the desired One Rate container types are configured in Supply Chain Cloud. (See Container Types for more information.)
Add a container type.
Select the desired container type from the prepopulated Ship Container Code drop-down list.
The External code is automatically generated. This aligns your Finance and Supply Chain Management setup with the carriers and services in Supply Chain Cloud.