Go to Setup, Search Escalation Rules in the Quick Find box, then select Escalation Rules. Here, you can also define Custom Escalation Rule as per your requirements.
Click on the New button for Creating an Escalation Rule.
Enter the Rule name as per requirement.
Specify Whether you want this rule activated on the Escalation rule, then click on the checkbox; otherwise, leave the active field.
Click the save button; your escalation rule will be saved in your Salesforce org.