As per the preview doc, we have enabled MetricsServer as a part of Featuregate for Openshift monitoring, 

We can add the hyperlink to how to enabled featuregate in the cluster which is mentioned in the document 

Example 

This release introduces a Technology Preview option to add a Metrics Server component to the in-cluster monitoring stack. As a Technology Preview feature, Metrics Server is automatically installed instead of Prometheus Adapter if the FeatureGate custom resource is configured with the TechPreviewNoUpgrade option. If installed, Metrics Server collects resource metrics and exposes them in the metrics.k8s.io Metrics API service for use by other tools and APIs. Using Metrics Server instead of Prometheus Adapter frees the core platform Prometheus stack from handling this functionality. For more information, see MetricsServerConfig in the config map API reference for the Cluster Monitoring Operator.