It is difficult to be specific without an outline of your needs. :-)
This article describes how to change your country setting and the requirements and results of doing this:
Click here --> Change your Apple ID country or region - Apple Support
Here are various issues and how to deal with them:
● Subscriptions
Make sure you have canceled all your subscriptions ( If you want to cancel a subscription from Apple - Apple Support ). However, subscriptions will then still continue until the expiration date. You need to contact Apple and request any ongoing subscriptions you have be ended immediately if you do not want to wait until they expire naturally.
● Spend all your Apple ID balance
One way to zero your balance is to add a credit or debt card as a payment method to your Apple ID and buy items just in excess of your remaining Apple ID balance. This will use up all the balance and any remainder will get charged to the card.
The other way is to contact Apple and ask them to keep any remaining balance.
● Pending purchases and refunds
If you have pending purchases, or refunds in the process of being returned to you, you will have to wait until these clear.
● Unusual case where having a child on Family Sharing may have prevented changing countries --> Error : “Your country/region cannot be ch… - Apple Community
For items where you need to contact Apple to resolve an issue:
Click here --> Choose your country or region - Official Apple Support Select your country, then a product. If you don't see one that handles your issue then keep experimenting with selections until you reach one that gets you a chat session or a telephone call and get the representative to redirect you.
or:
Contact Apple for support and service --> "See a list of Apple phone numbers around the world." Click here --> Contact Apple for support and service - Apple Support
