CODE EXAMPLE FOR PHP

wordpress show notice only on plugin page

function general_admin_notice(){
    global $pagenow;
    if ( $pagenow == 'options-general.php' ) {
         echo '<div class="notice notice-warning is-dismissible">
             <p>This notice appears on the settings page.</p>
         </div>';
    }
}
add_action('admin_notices', 'general_admin_notice');