Displaying dynamic pages using with Rewriting rule and Query vars

WordPress can create a rewrite rule natively. We want to make use of that to listen for a specific slug and if that slug is existing on on the GET query. Our task to provide a page template for that page to render on the screen.

But first, we need to make a new rewrite rule with the following scripts. In this script, we want to rule to slug called ‘custom’.

function bytescrafter_rewrite_rules() {
    add_rewrite_rule( 'custom/([^/]+)/?$', 'index.php?custom=true', 'top' );
}
add_action('init', 'bytescrafter_rewrite_rules');

Second, we need to register a query var on WordPress.

function bytescrafter_register_query_var( $vars ) {
    $vars[] = 'custom';
    return $vars;
}
add_filter( 'query_vars', 'bytescrafter_register_query_var' );

Third, we just need to display a specific template for that previously created slug for the custom page.

function bytescrafter_custom_template_include($template)
{
    //Load $wp_query object
    global $wp_query;
    
    //Check if query var is set and equal to target permalink.
    $page_value = isset($wp_query->query_vars['category_name']) ? $wp_query->query_vars['category_name'] : true;

    //Check if page is our target page hence return.
    if ($page_value == "jesus") {
        return get_stylesheet_directory().'/templates/custom.php'; //set the target template.
    } else {
        return $template; //Load normal template fallback
    }
}
add_filter('template_include', 'bytescrafter_custom_template_include', 1, 1);

Just take note that you can add this scripts on either your custom plugin or active theme’s function.php. For more WordPress codex tutorial, see Easiest way of having a site is WordPress for other WordPress codex tutorial.