Actions you can do from the operation bar:
Search a keyword
Enable hierarchy mode.
Change the number of issues per page.
Input a keyword then press Enter (Return for Mac) on your keyboard.
You can see Epic - Story - Subtask hierarchy in the Hierarchy View mode. In this mode, you can also collapse and expand the hierarchy. Parent-child relationship of WBS Gantt-Chart for Jira is also supported.
Hierarchy view is only available under "All" page size.