This is covered fairly well in the documentation at https://www.odoo.com/documentation/user/13.0/inventory/management/replenishment_strategies/virtual_warehouses.html
A specific example:
1. Your Manufacturing Warehouse needs these Resupply settings:
2. Your Distribution Warehouse needs these Resupply settings:
3. Your Finished Product needs these Routes, plus a Bill of Materials:
Note: The first Route will be created automatically for you.
4. You need two ReOrdering Rules:
Once you run the Scheduler, you will get two Transfers (a Delivery OUT of the Manufacturing Warehouse and a Receipt INTO the Distribution Warehouse) that use the Transit Location:
... and you will get a Manufacturing Order:
(You just have to make sure you have your Components in stock, and when you do the Material Availability will change to tell your Manager they can start the Manufacturing Order):