Normally you configure the Smarty settings by modifying the Smarty class variables. Furthermore you can register plugins, filters etc. with Smarty functions. Modifications done to the Smarty object will be global for all templates.

However the Smarty class variables and functions can be accessed or called by induvidual template objects. Modification done to a template object will apply only for that template and its included subtemplates.

<?php
$tpl = $smarty->createTemplate('index.tpl);
$tpl->cache_lifetime = 600;
//or
$tpl->setCacheLifetime(600);
$smarty->display($tpl);
?>

    

<?php
$tpl = $smarty->createTemplate('index.tpl);
$tpl->registerPlugin('modifier','mymodifier');
$smarty->display($tpl);
?>