I could, mustang, but I don't think this is the appropriate place for a full programming course.
@learnt, you're very new to programming. Learn programming before trying to program an Android app. You don't "make an app", you develop a program - that happens to be in Java/Kotlin and happens to use the APIs in Android. If you look at the API spec, you'll see all the information you're looking for. Or look at some of the sample programs, or some of the programs on YouTube. Interfacing wih the camera is the same as interfacing with any hardware, you just don't snap the shutter on the speaker.