Create Purchase order from customer order.

You can if you set up Purch Order Trans or Purch Order Dir as the Supply Codes on the Customer Order Line to run a process to automatically create a pegged purchase order to an outside supplier.  Likewise, you could use supply codes Int Purch Trans or Int Purch Dir as the Supply Codes for an Intersite or Intercompany automatic purchase process.  It isn’t as simple as just changing these codes however, you have to have all of the related objects and process details setup and validated prior to picking one of them.  This includes Customer Setup for Intersite Demand details from the demand site, Supplier Setup, Supplier for Purchase Parts, Sales Parts possibly, transit and delivery leadtime details, etc.

You could also indirectly trigger purchases from a Customer Order through the use of automatically released purchase requisitions and automatically created Purchase Orders, this is typically in conjunction with maintaining an agreement with a supplier who has agreed to supply the product on a regular schedule or to hold a certain amount of inventory.  In this case, the supply wouldn’t be pegged to the Customer Order, but could be driven indirectly from the customer order demand and consumption.

The short answer yes you can create a purchase order from a customer order, but the setup to get there is quite a bit more complex depending on which of the three scenarios you want to operate in.