Get_Page and Read More Tag

Hi all.

I’m using this code to call in content from a page:

<?php
$id = 38;
$p = get_page($id);
echo apply_filters('the_content', $p->post_content);
?>

Now when I add a read more tag into my posts (in the WordPress UI) it doesn’t show/work when viewing the site. The content is just fully showing.

Do I need to add something to the functions.php file or edit the code I posted above?

I checked the www.remarpro.com documentation but I don’t see what I should be using hence I’m asking you.

Thanks in advance.

Regards!