Disable public singular access for the 'arts_service' post type.

functions.php

<?php
/**
 * Disable public singular access for the 'arts_service' post type.
 *
 * Filters registration arguments to remove front-end exposure, flushes
 * rewrite rules on theme activation/switch, and cleans up the admin
 * edit screen for a consistent editorial experience.
 *
 * @package YourChildTheme
 */

/**
 * Disable public-facing arguments for the arts_service post type.
 *
 * Runs at priority 20 to ensure it fires after the registering plugin
 * (default priority 10), guaranteeing our overrides are applied last.
 *
 * @param array  $args      Post type registration arguments.
 * @param string $post_type Post type slug.
 *
 * @return array Modified registration arguments.
 */
function arts_service_disable_public_args( array $args, string $post_type ): array {
    if ( 'arts_service' !== $post_type ) {
        return $args;
    }

    $args['public']             = false;
    $args['publicly_queryable'] = false;
    $args['rewrite']            = false;
    $args['query_var']          = false;
    $args['show_in_rest']       = false; // Prevent REST API exposure.

    return $args;
}
add_filter( 'register_post_type_args', 'arts_service_disable_public_args', 20, 2 );


/**
 * Flush rewrite rules when the child theme is activated or switched to,
 * ensuring stale arts_service rewrite rules are purged immediately.
 *
 * Hooked to `after_switch_theme` which fires once on activation.
 * Avoid calling flush_rewrite_rules() on every request — it is expensive.
 *
 * @return void
 */
function arts_service_flush_rewrite_rules(): void {
    flush_rewrite_rules();
}
add_action( 'after_switch_theme', 'arts_service_flush_rewrite_rules' );


/**
 * Remove the "View Post" link from the post list table row actions.
 *
 * Prevents editors from following a now-inaccessible front-end URL
 * directly from the admin list screen.
 *
 * @param array   $actions Existing row action links.
 * @param WP_Post $post    Current post object.
 *
 * @return array Modified row actions.
 */
function arts_service_remove_row_view_action( array $actions, WP_Post $post ): array {
    if ( 'arts_service' === $post->post_type ) {
        unset( $actions['view'] );
    }

    return $actions;
}
add_filter( 'post_row_actions', 'arts_service_remove_row_view_action', 10, 2 );


/**
 * Remove the permalink HTML from the classic post editor title area.
 *
 * Suppresses the "Permalink:" line rendered beneath the post title input
 * on the arts_service edit screen, keeping the interface clean and
 * avoiding confusion over a non-functional URL.
 *
 * @param string $html    Existing permalink HTML markup.
 * @param int    $post_id Current post ID.
 *
 * @return string Empty string for arts_service; original markup otherwise.
 */
function arts_service_remove_permalink_html( string $html, int $post_id ): string {
    if ( 'arts_service' === get_post_type( $post_id ) ) {
        return '';
    }

    return $html;
}
add_filter( 'get_sample_permalink_html', 'arts_service_remove_permalink_html', 10, 2 );


/**
 * Intercept any residual front-end requests for arts_service posts.
 *
 * Acts as a defence-in-depth measure in case a cached or externally
 * generated URL reaches the front end before rewrite rules are flushed,
 * or if another plugin re-enables publicly_queryable at runtime.
 *
 * @return void
 */
function arts_service_block_singular_requests(): void {
    if ( ! is_singular( 'arts_service' ) ) {
        return;
    }

    global $wp_query;

    $wp_query->set_404();
    status_header( 404 );
    nocache_headers();
    include get_query_template( '404' );
    exit;
}
add_action( 'template_redirect', 'arts_service_block_singular_requests' );