Including interactivity (user inputs) in your AR experiences, especially when using 3D models, is key to engaging your user and maximising immersion. 3D models themselves listen out for when a user taps on them, and will initiate an assigned action once this occurs.
Adding Interactivity to 3D Models
Simply select the 3D model in the scene and assign an on-tap action to it.
To learn more about using action in your Designer project, check out this article.