Let's say you want to access the application shared preferences in /data/data/com.mypackage.
You could try to run adb shell and then run-as com.mypackage
( or adb shell run-as com.mypackge ls /data/data/com.mypackage/shared_prefs),
but on a production release app downloaded from an app store you're most likely to see:
run-as: Package 'com.mypackage' is not debuggable