How to make pagination in a custom template in WordPress?

Question

WordPress

There is no parent "Directive" page. There are only children of it. They come as pages, they have 1 common template template-directives.php. How to make pagination between them? In layout it looks like this:

<h1 class="h1"><a href="#"><i class="fas fa-long-arrow-alt-left"></i></a><?php echo get_the_title(); ?>:<a href="#"><i class="fas fa-long-arrow-alt-right"></i></a></h1>

Or maybe display them through custom posts?