We could simply store the value (arabic) locally in the device and when you relaunch the app you should have a functionality to get the previous stored value which provides you the state you want.

Now, there pretty awesome package to do all those stuff for you for example (easy_localization) which makes localization in flutter easier.

Or you can continue with this, but use a package to store the value locally for example (get_storage).

I hope I made things clearer for you.