Task Planning App that lets you create tasks under sub-tasks?

Web: https://www.reddit.com/r/productivity/comments/ulh9ed/task_planning_app_that_lets_you_create_tasks/

I've been using Microsoft To Do and it's been great since it integrates with my Outlook calendar.

The issue is it only lets me break down tasks into sub-tasks. I work on large projects so often sub-tasks require a bunch of smaller tasks in order to complete and I need some way to track this. Is there a productivity/task planning app out there that lets you create another level of tasks under the sub-tasks?

app planning productivity