You can only set an ID to one country at a time. You can change country settings but this can be tedious if done frequently.
The article "Change your Apple ID country or region" describes how to change your country setting on everything using your Apple ID, and the requirements and results of doing this --> Change your Apple ID country or region - Apple Support
The other route is to set up an ID in each country but then it too is tedious if you are using mobile devices which can only hold one ID at a time.
Generally content that is on a device will stay on a device and will work. The only issues may have to do with particularities as to settings if you encounter such. Of course you can't update those apps if the app isn't available in the other country.