I don't know how to formulate this question but I'll give it try.
I have a complete Splunk Enterprise installation on Site A and another complete Splunk Enterprise installation on Site B.
On-Site A I have Indexer, Search Heads, and License Server. Same on Site B with Indexer, Search Heads, and License Server.
The two environments are separated from each other with firewalls.
Is there a way that the Search Head from Site A can access to an Indexer (Search Peer) on Site B?
Yes, you can just add the indexer(s) from site B as search peers in your search head:
https://docs.splunk.com/Documentation/Splunk/7.3.1/DistSearch/Configuredistributedsearch
As long as it can access the indexers (firewall not blocking it).
Hi kmorris
Thank you for your answer.
Will, it also work if the two sites have different licenses