If you would like to change the default country in the final booking form field you can add the below-given code in your child theme functions.php file. To know how to create the child theme please refer to the below-given link: 

Child Theme  

After creating the child theme in your child theme functions.php file add below-given code.

function wp_travel_customize_booking_form($fields) {
	$fields['traveller_fields']['country']['default'] = 'NL';
	$fields['billing_fields']['country']['default'] = 'NL';
 
	return $fields;
 }
 
 add_filter( 'wp_travel_checkout_fields', 'wp_travel_customize_booking_form', 99 );

You need to replace ‘NL‘ country code with your country code in the above-given code.

For more detail regarding changing the default country in the form field, please free to our Knowledge Base.