Yes, if you change the region or country associated with your Apple ID, it will affect all devices that share the same Apple ID. Here’s what happens:
1. App Store & iTunes: The App Store and iTunes content (such as apps, music, movies) available to you may change depending on the region. Some content available in one region may not be available in another.
2. Subscriptions & Services: Services like Apple Music, iCloud, and other subscriptions may be affected. You might need to cancel some subscriptions and re-subscribe in the new region.
3. Payment Methods: You’ll need to update your payment methods to one that is valid in the new region.
4. Content Availability: Previously purchased content might not be available or may need to be re-downloaded if it is available in the new region.
Because the change applies to your Apple ID, it affects all devices that are signed in with that account, not just the phone where you made the change.
Axel F.