can we edit existing extractor tap-elasticsearch

You mean this one right? https://hub.meltano.com/extractors/tap-elasticsearch First of all: Yes of course, it is open source. This particular connector is an airbyte connector (repository here: https://github.com/airbytehq/airbyte/tree/master/airbyte-integrations/connectors/source-elasticsearch) and is written in Java. Depending on your use case it might also be quite easy to just write your own Python based tap using the SDK. Elasticsearch does have a python client.