By default, Jira Software default hierarchy contains:

• Epics - Once the higher-level priorities are settled it's necessary to break them down into large pieces of work, which consist of multiple stories.
• Stories/Tasks - User stories capture functionality requirements.
• Sub-task - Work components that makeup stories.

Currently, Advanced Roadmaps offers the ability to create new, unlimited hierarchy levels as well as getting a 'big picture' view of your projects and tasks in Jira Software or Jira Core, but it uses custom issue types at the same level of "Stories/Tasks" and it was an adaptation provided by the Advanced Roadmaps tool.

As a Jira Software user, I want to be able to create hierarchy levels directly in Jira Software, without the necessity of the adaptation of the level of "Stories/Tasks".