How to Modify WP_Includes/blocks/latest_posts.php

This really depends on your theme. Somewhere in its template files the title is generated, including the anchors. This differs per theme, but you’ll have to look for something like this:

echo '<a href="'. get_permalink . '">' . get_the_title . '</a>';

If it is hard coded like this, you’ll have to choice but to override it by making a child theme, copying the template file where you found this and replace it with

if (is_front_page) echo get_the_title;
else echo '<a href="'. get_permalink . '">' . get_the_title . '</a>';

Note that, depending on the theme, things may be a lot more complicated than this.