Wordpress - Pagination when using wp_query?

Replace <!-- WHAT GOES HERE?????? --> with the pagination code below:

<div class="pagination">
    <?php 
        echo paginate_links( array(
            'base'         => str_replace( 999999999, '%#%', esc_url( get_pagenum_link( 999999999 ) ) ),
            'total'        => $query->max_num_pages,
            'current'      => max( 1, get_query_var( 'paged' ) ),
            'format'       => '?paged=%#%',
            'show_all'     => false,
            'type'         => 'plain',
            'end_size'     => 2,
            'mid_size'     => 1,
            'prev_next'    => true,
            'prev_text'    => sprintf( '<i></i> %1$s', __( 'Newer Posts', 'text-domain' ) ),
            'next_text'    => sprintf( '%1$s <i></i>', __( 'Older Posts', 'text-domain' ) ),
            'add_args'     => false,
            'add_fragment' => '',
        ) );
    ?>
</div>

WordPress comes with a handy function called paginate_links() which does the heavy lifting. In the example above, the custom WP_Query object $query is used instead of the global $wp_query object.

This code is for Custom Query Pagination. You can follow the steps to create your own pagination in WordPress.

 <?php
/**
* Template Name: Custom Page
*/
get_header(); ?>

<?php
$paged = ( get_query_var( 'paged' ) ) ? get_query_var( 'paged' ) : 1;
$args = array(
  'posts_per_page' => 4,
  'paged' => $paged
);
$custom_query = new WP_Query( $args );
?>
          <!----start-------->
<div class="wrap">
<div id="primary" class="content-area">
<main id="main" class="site-main" role="main">

<?php
   while($custom_query->have_posts()) :
      $custom_query->the_post();
?>
       <div>
        <ul>
         <li>
           <h3><a href="<?php the_permalink(); ?>" ><?php the_title(); ?></a></h3>
        <div>
          <ul>
        <div><a href="<?php the_permalink(); ?>"><?php the_post_thumbnail('thumbnail'); ?></a></div>
          </ul>
          <ul>
        <p><?php echo the_content(); ?></p>
          </ul>
        </div>
        <div>
          </li>
        </ul>
          </div> <!-- end blog posts -->
       <?php endwhile; ?>
      <?php if (function_exists("pagination")) {
          pagination($custom_query->max_num_pages);
      } ?>
</main><!-- #main -->
</div><!-- #primary -->
</div><!-- .wrap -->
          <!----end-------->
        <?php get_footer();

Reference : https://www.wpblog.com/use-wp_query-to-create-pagination/