If you want to write an Android app that interacts with the camera beyond merely taking a picture or shooting some video, you’ll want to make use of the Camera2 API, which became available at API level 21 (a.k.a. Android 5.0, a.k.a. Lollipop), which goes all the way back to late 2014.
There are a number of recently published articles and documents that you can consult if you’d like to explore Camera2: