Can Closed PO Lines be Updated to Finally Closed Status via REST API?

I attempted following available Procurement REST API documentation for the below suggested Endpoint of:

/fscmRestApi/resources/11.13.18.05/purchaseOrders/{{POHeaderID}}/child/lines/{{POLineID}}

and updating "FinalCloseFlag": true ; however, I continue to encounter 403 Forbidden errors and confirmed via GET calls that the PO details in question are available and can return data. The user account performing the REST calls does have Procurement Application Administrator and Buyer security access and corresponding Data Access to the Procurement Business Units in question. I also attempted performing the same steps for the Line Locations first, but the same error persists.

Is it possible to perform REST API calls to update Closed status PO lines to Finally Closed status? Or is this something that can only be accomplished via the UI?