The structure of the organization I currently belong to is as follows.
First, write the name of the project at the top and
Below that, write down the assigned roles for the project.
There is a large chunk of work distributed to each role below, but there are no problems up to this point. However, I want to add detailed tasks within a large chunk, but no more sub-issues are created. It would be great to have just one more depth, but the lack of one sub-issue makes it difficult to work efficiently and is disappointing from the user's perspective.