I'm trying to understand if enabling clustering helps improve the search experience. If clustering is enabled, then would the results (served by sitecore) change in anyway?
It seems a new facet is made available by which we can refine data by a cluster, but this article says that the facet is available only in Interface Editor. So again, I don't know how would then help the end user experience. I would really appreciate any documentation on this.
Clustering doesn't affect the results returned nor their order. It simply enables a new facet to be displayed that contains "subjects".
Clustering can be enabled on a Coveo Search API REST query (see enableClustering).