How to make that: "Model template"?

I am not sure for what I must search to find what is behind this feature: There is an additional menu item to create a subtree:

Is there a doc about that feature?

Hi, it seems this is the relevant doc

ok thank you!

The given document does not show where the default items come from when e.g. using it with “Product Management”. If I enable it for another item, it is simply empty.

Oh I found it:

2020-07-24 09_08_22-Posteingang - - Outlook