Calculate age PHP function

calc_age.php

<?php
function ageForDate(string $dob, string $date = 'today', bool $years_only = true): string
{
    $from = new DateTime($dob);
    $to = new DateTime($date);
    $interval = $from->diff($to);
    if ($years_only) {
        return $from->diff($to)->y;//years
    } else {
        return $from->diff($to)->y . '.' . $from->diff($to)->m;//years.months
    }
}

echo ageForDate('1985-04-28', 'today', false);