Hi @anon84082955,
First of all welcome to the forum! Second, it is great to see that you value subtasks for organizing your projects.
There is an existing thread regarding this that is almost to 1,000 votes. I would add your voice in here! Timeline - Schedule Subtasks - #42 by Sarah_Gregory
What do you mean by levels?
There is another thread regarding this request as well! Ability to view assigned SUBTASKS in Portfolio>Workload