In wp-config.php add:

define('WP_CONTENT_FOLDERNAME', 'my_new_content_folder');
define('WP_CONTENT_DIR', ABSPATH . WP_CONTENT_FOLDERNAME);
define('WP_CONTENT_URL', 'https://' . $_SERVER['HTTP_HOST'] . '/' . WP_CONTENT_FOLDERNAME);

Source: https://developer.wordpress.org/advanced-administration/wordpress/wp-config/#moving-wp-content-folder