See Related Work at a Glance with Case Hierarchy
Where: This change applies to Lightning Experience in Essentials, Professional, Enterprise, Performance, Unlimited, and Developer editions. Case hierarchy is not available in Communities.
Who: Give your users read permission on cases and set the field-level security for the Case Parent field to read.
How: Edit the case page layout and add the Parent Case field and the View Case Hierarchy action to Salesforce Mobile and Lightning Experience Actions.
You can choose which case fields to show as Hierarchy Columns. By default, the hierarchy view uses the same columns as the recently viewed cases list view.