How to change Apple ID region?

To change your region you will need to fulfill certain requirements:

What to do before you change your country or region

• Spend any balance remaining on your Apple ID. If you're not sure whether you have a balance, check your Apple Account balance.
• Cancel your subscriptions and wait until the end of the subscription period. 
• Wait for any memberships, pre-orders, movie rentals, or Season Passes to complete, and wait for any pending store credit refunds to process. You can cancel a pre-order.
• Make sure that you have a payment method for your new country or region. See what payment methods you can use.
• Redownload your apps, music, movies, TV shows, and books on any devices that you might use to play or read them in the future. Some types of content might not be available in your new country or region. Learn what types of content and services are available in your new country or region.

If you meet all of this requirements please see this :

Use your iPhone or iPad to change your region

1. Open the Settings app. 
2. Tap your name, then tap Media & Purchases.
3. Tap View Account. You might be asked to sign in.
4. Tap Country/Region.
5. Tap Change Country or Region.
6. Tap your new country or region, then review the Terms & Conditions.
7. Tap Agree in the upper-right corner, then tap Agree again to confirm.
8. Select a payment method and enter your new payment information and billing address, then tap Next. You must enter a valid payment method for your new country or region.*

See this link for further reference

Change your Apple ID country or region - Apple Support

The article Change your Apple ID country or region - Apple Support describes how to change your Apple ID country or region, and the requirements and results of doing this.

You may encounter various issues and here is how to deal with them:

● Subscriptions

Make sure you have canceled all your subscriptions (see: If you want to cancel a subscription from Apple - Apple Support ). Wait for any memberships, pre-orders, movie rentals, or season passes to complete. Items will still be active until their expiration date. You need to contact Apple and request any ongoing items you have be ended immediately if you do not want to wait until they expire naturally.

● Remove all your Apple Account balance

- In the main change country article Apple only proposes a single way for you to clear your balance. That is to contact them and ask them to keep it. Apple offers this specific link for that service --> https://getsupport.apple.com/?caller=kbase&PGF=PGF63005&category_id=SC0998&symptom_id=20198

- Another still viable way 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 excess will get charged to the card, leaving nothing in your account.

● 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.

● Leave or disband any Family Sharing groups.

Refer to Leave Family Sharing - Apple Support

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:

See a list of Apple phone numbers around the world. Click here --> Contact Apple for support and service - Apple Support