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

Adding a new object attribute to the Application ObjectConfig in IdentityIQ is not sufficient on its own to generate the database script needed to extend Application attributes. This action updates the configuration within IdentityIQ for how the application object is managed, but it does not produce the necessary SQL scripts to modify the underlying database schema. The actual database schema must be extended using specific IdentityIQ tools and commands like iiq extendedSchema.

SailPoint IdentityIQ Configuration Guide (ObjectConfig and Schema Management)

SailPoint IdentityIQ Administration Guide (Database Schema Extension)