Can’t change region

In order to change your country and region, you Will need to fulfill certain requirements. See them Below

• 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.

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.

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 ). 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.

● 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.

- Another 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