latest posts in posts

Did you check: get_posts
example:

<?php
 $postslist = get_posts('numberposts=10&category=1');
 foreach ($postslist as $post) :
    setup_postdata($post);
 ?>
 <div>
 <?php the_date(); ?>
 <br />
 <?php the_title(); ?>
 <?php the_excerpt(); ?>
 </div>
 <?php endforeach; ?>

You could use keesiemeijer’s code in a post if you use a plugin such as Exec-PHP.

Or try https://www.ads-software.com/extend/plugins/list-category-posts/

I went to fast and read over the “(not on the post template)” bit. Try MichaelH solution.