Hi @Andy15,
Asana does not currently provide for such “task templates”. It’s a popular request, and you can add your vote for it here:
FYI there is a capability somewhat similar available in my Flowsana integration - “subtask templates” - it will copy a set of predefined subtasks onto an existing task, as the result of a Flowsana rule being triggered. You can see more about it here. (I’m considering adding a similar capability for task templates.)