Visit https://account.apple.com/, click "Create Your Apple Account" in the top right corner, and create an account using a new email address. You can use your current phone number.
Log in to https://account.apple.com/ with your new account, then go to "Personal Information" → "Country / Region" → "Change country or region".
Select United States as the country and fill in a random U.S. address. Click "Update" to save. You can use one of the following free U.S. address generator websites to generate a U.S. address:
After switching, keep the main account signed in on your device, open the App Store, tap the Account icon in the top-right corner to access the account settings page.
Scroll down and tap Sign Out to log out of the current account. After logging out, tap Sign In and enter the Apple ID account information you just created.
This will allow you to download free apps from the U.S. region while keeping your original account logged in.
Note 1: If an Apple ID security prompt appears, tap Other Options → Don't Upgrade.
Note 2: If a prompt asks you to answer security questions, do not answer; simply close the prompt and return to the previous step.
Note 3: If you're logged into another account, please first follow the sign-out process.