I’ve been using asana for many years. There used to be a default in the “Later” section that organized tasks by project. I don’t see a way to do that now. I am using the free version of asana.
I believe this was changed quite a while ago with My Tasks v2.
All you can do now is sort all of My Tasks by project (regardless of section).
The way many use Later, they don’t need that capability, and Asana doesn’t really recommend it (judging by their removal of the feature).
In case you’re interested, I wrote a guide for moving to My Tasks v2 when it was released and many still find it a useful way to approach My Tasks: