Is there a way to view the logs of the REST API calls made from external system to CX?

You can view a log of all REST API calls made from an external system to Oracle Sales cloud using the Oracle Cloud Infrastructure Audit service. The service automatically records calls to all supported Oracle Cloud Infrastructure public application programming interface (API) endpoints as log events. Log events recorded by the Audit service include API calls made by the Oracle Cloud Infrastructure Console, Command Line Interface (CLI), Software Development Kits (SDK), your own custom clients, or other Oracle Cloud Infrastructure services.

Each log event includes a header ID, target resources, timestamp of the recorded event, request parameters, and response parameters. You can view events logged by the Audit service by using the Console, API, or the SDK for Java. For more information, see Audit logs.