You may need to add code, such as google structured data/rich data into a specific page header <head> </head> while keep the original header.
This can be done via edit the backend template file, such as a category file category.php in your theme folder.
In the page php file add below to top:
<?php
add_action('wp_head', 'your_function_name');
function your_function_name(){
?>
PASTE HEADER CODE HERE
<?php
};
get_header();
?>