I want to add either Salesforce developer org or Sandbox Org into Social studio . Then want to use it in Engagement macros so that i can test Lead and case creation In Service cloud from social studio Engage Tab.
Yes, you can:
Configure Social Studio Automate to connect to one or more Salesforce orgs. Once connected, you can enable automated rules to send posts directly to those orgs and open them as new cases.
You can connect Social Studio Automate to one or more production or sandbox Salesforce Orgs.