How to execute custom logic in extension graph after Process or ProcessAll button functionality completed

Hi @ShahidaValiSyed04  You can try like below.

 public class ProductManualExtension : PXGraphExtension<ProductManual>
    {

        public override void Initialize()
        {
            Base.VIEWNAME.SetProcessDelegate(
               delegate (List<DACNAME> list)
               {
                   ImportRecords(list, Base.Filter.Current);
               });
        }

 public void ImportRecords(List<DACNAME> list, ImportProductFilter currentFilter)

{

         //Logic here

}