The sample app comes with built-in "feature" behaviors - meaning - if you launch the app and tell it to run as feature 1, 2, or 3 to show slightly different behavior. A feature is set using a Docker build argument that sets an environment variable that the application code looks for. You can read more about this in the demoapp README file.
To change feature numbers, adjust the environment variable FEATURE_NUMBER to the value in the pipeline.yml file and commit the code change. JFrog will automatically re-run the pipeline after any code commit, so just monitor the progress of the pipeline and then go back to review the Dynatrace release inventory, events, and JFrog artifacts. Below is an example of what the change should look like: