One semantic model that reads data from other semantic models

Is this a composite model? As I understand there will be Direct Query involved in this case. Let's say we have a case:

Logistics Semantic Model (Import mode)
Sales Semantic Model (Import mode)
Report Semantic Model that reads data from Logistics Semantic Model and Sales Semantic Model

Is the direct query happening between the Logistics/Sales Semantic Model to the Report Semantic Model? The Logistics/Sales Semantic Models are still import? How is the speed for this?

What happens if I in my Report use a measure from the Logistics Semantic Model - is that measure working under the limitions of DQ? Is there a difference between how the measures in Logistics/Sales Semantic Models work compared to a new measure in Report Semantic Model that combines data from Logistics & Sales?

What happens if there is RLS in Logistics/Sales Semantic Models?