Is this what should be performed in order to generate the database script to extend...

Running a build with the updated schema placed inside it is not the correct procedure to generate the database script to extend Application attributes in the IdentityIQ database during the initial installation. To extend the schema, you typically need to define the changes in a specific XML schema file and then generate the corresponding database scripts using IdentityIQ tools designed for schema extension. A build process does not inherently generate the required database scripts for extending attributes.

SailPoint IdentityIQ Schema Configuration Guide

SailPoint IdentityIQ Installation and Setup Guide