How to modify Procurement (Requisition Page) through application composer or though Groovy Script

We have a requirement where on the selection of DFF value, It should split and auto populate into Project Number and Task Number which is a standard field in the requisition page. Can we achieve this through Groovy Script ?

We are unable to see Procurement in Application Composer under Standard Object. Can we modify it through Application Composer?

Please provide any reference or document if any