How to pass a value with POST from a PHP file to another one?

I have a scenario where I want to pass a value AND redirect from the authentication.php file to index.php file without using GET but only POST. I want to keep it hidden from the user.

I thought about using cURL but as far as I know this will execute the index.php file, right?

// set post fields
$post = [
    'customer' => 'username',
    'token' => 'token123'
];

$ch = curl_init('www.domain.com/index.php');
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, $post);

// execute!
$response = curl_exec($ch);

// close the connection, release resources used
curl_close($ch);

PS: I dont want to use SESSION nor COOKIES. I understand that COOKIES can be encrypted but I still dont prefer to use them.

So, is there a good way for doing this?

source https://stackoverflow.com/questions/68581273/how-to-pass-a-value-with-post-from-a-php-file-to-another-one