Regex Multiple names validation

expression.php

<?php
// Expression
$expression = '/^([_\p{Lu}\p{Lt}][_\p{Nd}\p{Ll}\p{Lm}\p{Lo} ',-."]+)+$/u';

$rules = [
        'full_name' => 'required|regex:' . $expression,
        'first_name' => 'required|regex:' . $expression,
        'last_name' => 'required|regex:' . $expression
  ];

// Allows all names https://www.w3.org/International/questions/qa-personal-names
// Except Chinese characters...
// Allows names such as Jan Hendriks Willemsen
// Allows names such as Zoë Jans Janssen
// Allows names such as D'arcy d,o-s santos
// Does not allow JAN HENDRIK WILLEMSEN