Java Question Access foreign or other app's db file with rooted phone

can I get access to another foreign app's db file, if I'm operating my app from a rooted phone, w root access? In the context of the FileProvider method of access, It is not possible to have the foreign app return me the db file with an intent, but I have root access for my app. How should I go about this?

Accessing Root folder needs Administrator privileges.

I presume I get root privileges once I root the phone. I was thinking of using the superuser class to do a chmod on the other app's db file, and directly access it.
When I connect to the phone via adb, I can already access the /data/system folder. The only other thing I am unsure of, is whether the foreign app can still access the database, once I alter its database file privileges. Once I alter the database file, it should now belong to me, right?