Canda & USA is the default country. "number" should be the number field's ID

Add Country Code with Flag in Elementor Forms

HTML widget 1:

<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/intl-tel-input/18.5.0/css/intlTelInput.css">
<script src="https://cdnjs.cloudflare.com/ajax/libs/intl-tel-input/18.5.0/js/intlTelInput.min.js"></script>

HTML widget 2:

<script>
jQuery(window).on('elementor/frontend/init', function () {
  elementorFrontend.hooks.addAction(
    'frontend/element_ready/form.default',
    function ($scope) {

      if (typeof window.intlTelInput === 'undefined') return;

      const phoneInput = $scope.find('#form-field-number')[0];
      if (!phoneInput) return;

      if (phoneInput.classList.contains('iti-initialized')) return;

      window.intlTelInput(phoneInput, {
        initialCountry: 'ca',
        separateDialCode: true,
        preferredCountries: ['ca', 'us']
      });

      phoneInput.classList.add('iti-initialized');
    }
  );
});
</script>