Clone production cluster

I'm new to elasticsearch and would like to know the best way to do this
basically I'm trying to clone a production cluster and then use it for testing
it needs to be a complete copy and should not interrupt the production cluster
I thought about adding a new node to the production cluster and increase the number of replicas then separate that node and rename it as a new cluster
Is there a better way?

Use the snapshot and restore mechanism and two completely separate clusters. The approach you described is not supported and unlikely to work, at least if you have a reasonably recent version of Elasticsearch.