Do I have to create contract types to author contract terms on purchase orders or sourcing documents such as RFQs?

To author contract terms on individual purchase orders or other Oracle Fusion Sourcing documents, such as RFQs, you aren't required to set up contract types. This is because no enterprise contracts are created.

The documents themselves are the contracts. All setups to enable contract terms templates and contract terms authoring are done from within Oracle Fusion Purchasing and Sourcing applications.