Age is displayed on a contact record but only DOB is a token available in message templates.
Are there any extensions that make age available for use? I've not been able to locate anything.
This sounded like a useful feature, so I added Age tokens to Eileen's CiviTokens extension, which seems to be the most widely used extension of its kind. Until a new release comes out, you'll have to pull from the master branch of the git repo.
I don't see any either, but the code to use in such an extension (as either a token or even a smarty modifier) seems pretty straightforward:
https://github.com/civicrm/civicrm-core/blob/5.19.2/CRM/Contact/BAO/Contact.php#L2677-L2684
if ($contact->birth_date) {
$birthDate = CRM_Utils_Date::customFormat($contact->birth_date, '%Y%m%d');
if ($birthDate < date('Ymd')) {
$age = CRM_Utils_Date::calculateAge($birthDate);
$values['age']['y'] = CRM_Utils_Array::value('years', $age);
$values['age']['m'] = CRM_Utils_Array::value('months', $age);
}
}