I want to add country code width to phone number text field at checkout add new address popup.Any one help me on this
Here is the some free and paid extension available, you can use it:
If this post is use full then please accept my post.
Check this extension, it will help you to resolve your requirements.
You can use the below extension, it automatically adds validation based on the selected country with the country flags and automatically sets the user country by default based on their Geo IP location. It is also supported with the latest Magento 2.4.5 version as well.
You can purchase this extension here https://www.giaphugroup.com/magento-2-country-calling-code-and-flag-extension.html
it will help to resolve your requirements fast.