If you are willing to rename Book Now button in single Itinerary page then WP Travel plugin provides the feature regarding renaming Book Now button in single Itinerary page using filter code as per your requirement.

To rename Book Now button, you have to add following given code in the functions.php file of your child theme.

function wp_travel_customized_strings( $strings ){
   $strings['featured_book_now'] = __( 'Your Text here' , 'wp-travel' );
   return $strings;
}
add_filter( 'wp_travel_strings', 'wp_travel_customized_strings' );

For detail assistance regarding creating child theme, please refer link.

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