Automation uses simple WHEN/IF/THEN logic to trigger actions based on criteria that you choose.
It's important to note there are two types of automation Service Desk Automation and Automation for Jira.
Automation for Jira offers significant advantages over Jira Service Desk's in-built automation, it enables you to capture even more business requirements. I recommend creating custom rules with Automation for Jira, however, the Service Desk build-in automation does have rule templates that you can easily create. Review the documentation below and select which is best for your project and rule.