In your theme, you’ll need to most likely modify the “header.php” template. It should include the tag of html output for every page of the site.
Within the tag, you can use a conditional call to check the result of both the queried object type and id using: get_queried_object().
For instance, you would have some php like this in the tag of header.php:
<?php
$queried_object = get_queried_object();
//check to see that the object is not an archive page or category page, but an individual post or page
if(! empty( $object->post_type )) {
//conditionally check that it is the specific page you want to target
if($object->queried_object_id == [specific post/page ID]) :
?>
[your custom metatags]
<?php else: ?>
[standard metatags if hardcoded, otherwise, include php function to render wordpress theme generated ones]
<?php endif; ?>
<?php endif; ?>
For more info regarding:
- get_queried_object() function, see the Function Reference/get queried object Codex page.
- get_queried_object class, see the WP_Query::get_queried_object() Codex page.