Login to cPanel and scroll down to the Software section. Click on Select PHP Version. Under My Domains, you will see all domains and subdomains in your account listed. In the Handled By column, you will see which platform is handling PHP for that domain or subdomain.

In most cases, you will probably see a cPanel logo and a PHP-FPM logo. If you see this, then you will need to use MultiPHP to manage PHP.

If you see the Cloudlinux logo, the domain or subdomain is using PHP Selector.