How to make the changes only in test and verify without deploying it to dev environment?

Summary:

I have created an application extension using visual builder studio test environment.
I have created a deploy build to push the application extension from test to dev environment.
When deployed I could see that the application is available in dev environment but the application code is available in test VBS.
How to make changes only in test and verify without deploying it to dev environment.

Consider I want to make a change in the application extension:
I have created a branch and made the changes in test environment and merged with main.
How to deploy the application in test and later deploy it to test.