I have a Galaxy S7 and it is locked so I can't add new languages. Can someone tell me if this is possible without root?
Even though your device is locked, you can add languages that comes with TouchWiz UI. I am not sure for input language or total language change from English to your choice you are asking but I think this article on Samsung Galaxy S7 & S7 Edge tips will help you. There, you need to scroll till the bottom.
You can do it without root like this
- Download MoreLocale2
adb shell pm grant jp.co.c_lis.ccl.morelocale android.permission.CHANGE_CONFIGURATION
Change the device's language from MoreLocale app