By default, the Gateway stores the metrics in the internal database. You can configure the Gateway to store the metrics on an external database. You can use your analytics tool, like Grafana, to view the metrics in detail.
The documentation explains configuring external service metrics: https://techdocs.broadcom.com/us/en/ca-enterprise-software/layer7-api-management/api-gateway/10-0/learning-center/overview-of-the-policy-manager/gateway-dashboard/configure-gateway-for-external-service-metrics.html
The sample policy on this page may not be enough for a complete test. So, you can use the attached policy to test this use case.
Release : 9.4 and above
Component : API GATEWAY
This policy is gathering the metrics and sending it to the external InfluxDB. The metrics data on this DB can be used to view with any analytics tool.