Hi @ZachSav,
Welcome to the forum!
I’m wondering how agile a project can be when it has phases.
But to your question I think you can find a lot of the building blocks you need here: Leveraging project templates - a deep dive
The automatic assigning could be done with rules adding subtasks before turning the task into a project.
Dividing it in phases/sections automatically might prove challenging. But if you’re ok with using a custom field for the phase instead of a section it should work.
Kind regards,
Jan-Rienk