Yes, the blanket permission in WWII is what allowed Eisenhower to accept the boatload of orders and decorations he was offered at the end of the war.

In 1966, Congress gave blanket permission government-wide "to the accepting, retaining, and wearing by an employee of a decoration tendered in recognition of active field service in time of combat operations or awarded for other outstanding or unusually meritorious performance, subject to the approval of the employing agency of such employee."

The President is included in this blanket permission, but I'm not sure who he has to ask for approval as the head of his employing agency. As I said, most if not all Presidents have accepted foreign orders and decorations only after leaving office.