How to set the Last-Modified header?

Question

1C-Bitrix

It is necessary to set the title for the sections of the catalog / product card equal to the date of the last modification.
placed the code in init.php

header('Last-Modified: '.gmdate('D, d M Y H:i:s', $last_modified_time).' GMT');

But so that I do not pass in $last_modified_time - the current time is always transmitted in the header when requested.
You can set this header in Bitrix. If possible how

Answer 1

and why through init?
add a header to the component template, especially since these data are available there without additional functionality