php validate date format

$date="2012-09-12";

if (preg_match("/^(20[0-9]{2})-(0[1-9]|1[0-2])-(0[1-9]|[1-2][0-9]|3[0-1])$/",$date)) {
    return true;
} else {
    return false;
}

function isValidDate(string $date, string $format = 'Y-m-d'): bool
{
    $dateObj = DateTime::createFromFormat($format, $date);
    return $dateObj && $dateObj->format($format) == $date;
}