When i click on ElasticSearch as source it has fields like
Basic Auth Password
Basic Auth User
Base URL
Could you help me where these details available at AWS console? Is Base URL the endpoint?
Also, what access policy i have to set at ElasticSearch to query from Redash?
The Base URL is the endpoint. As for the access policy - you will probably need to allow access based on the IP address of the Redash host. There might be other options, you should refer to AWS ElasticSearch documentation.