What is the proper pattern for a singleton SETTINGS class load using composer?

Question

I have a class file Settings.php that loads an ini file and assigns the content to a constant for global access and reducing clutter. The class file contains the logic for loading the settings and define the constant (sorry for the large sample didn't see a way to compress this:

<?php declare(strict_types=1);
namespace Utils;
if( !defined( SETTINGS ) ) {
 if( !defined( 'SETTINGS_FILE' ) ) {
 define( 'SETTINGS_FILE', $_SERVER[ 'DOCUMENT_ROOT' ] . '/settings.ini' );
 }
 class Settings
 {
 public static function getSettings(): array
 {
 return parse_ini_file( SETTINGS_FILE, true );
 }
 }
 define( 'SETTINGS', Settings::getSettings() );
}

With the composer auto loader included the Settings class gets loaded with \Utils\Settings-> getSettings(); and as side effect the SETTINGS is available with the content of the settings.ini file or another one if specified in SETTINGS_FILE.

This works and something like SETTINGS['db']['username'] is available which is a nice compact and highly self-documenting access to the settings. I wonder however if this code smells in any shape or form and if there is a better way to do this.