add_action( 'admin_notices', 'wpse332074_donotedit' );
function wpse332074_donotedit {
  if (is_page('ID-of-forbidden-page')) {
    $class = 'notice notice-error';
    $message = __( 'Do not edit this page!', 'your-text-domain' );
    echo '<div class="' . $class . '"><p>' . $message . '</p></div>';
    }
  }

add_filter ('edit_post_link','wpse332074_disable_edit',10,3);
function wpse332074_disable_edit ($link, $ID, $text ) {
  if ($ID == 'ID-of-forbidden-page')) return '';
  }