Hi @usmanshahzad
You only need to add it to the end of the link like this:
wp_redirect( 'http://localhost:8888/wordpress/thank-you/?thankid=' . $post_id ); exit;
And in the thank you page template, you can get the ID like this:
$new_post_id = $_GET["thankid"];
And then use it with the get_field() function like this:
$name = get_field('custom_field_name', $new_post_id );
echo $name;
Where “custom_field_name” is the name of the custom field.
I hope this helps.