I can't change my iPhone 13's country region

—First—

Make a request to zero out any remaining balance on your account by contacting Customer Support by phone or chat:

• Chat now or call 1-800-APLCARE.
• International Support.

—Next—

Cancel your subscriptions and wait until the end of the subscription period. 

—Then—

Click ▶︎ Change Region. 🌐

Hello ~ Take a look at this helpful link below by clicking on…

Change your Apple ID country or region - Apple Support

Work through all of the steps listed in the article.

~Katana-San~