Create a specific approval flow for the PO that was released from the agreement

I am trying to build two different approvals flow for the POs

1- PO that released from a specific agreement( regardless if it was CPA or BPA)

2- A direct PO that is not referring to an agreement

I need a way to do that without going through workaround (creating DFF and let the Buyer select the flow for his PO referring if there is an agreement or not)