i already have a working app but i need to ask for permission for use of camera, location and access to contact
You will have to add permission in config.xml later that will be added in androidmanifest,xml
Read the plugin readme/docs otherwise use cordova diagnostic plugin
I really advise to use the Diagnostics Plugin. You can easily check and ask for permissions at Runtime.
This is the error i get after following camera implementation on https://ionicframework.com/docs/developer-resources/guides/first-app-v3/ios-android-camera
You are testing on a Desktop? The Camera Plugin only works on a real Device