Bootstrap 4 navigation part for WordPress (loosely based on https://gist.github.com/mtx-z/f95af6cc6fb562eb1a1540ca715ed928)

wp-bootstrap-pagination-part.php

<nav aria-label="pagination">
  <?php
    global $wp_query;
    $entries = paginate_links([
      'base'         => get_pagenum_link(1) . '%_%',
      'format'       => '?paged=%#%',
      'total'        => $wp_query->max_num_pages,
      'current'      => max( 1, get_query_var('paged') ),
      'show_all'     => false,
      'type'         => 'array',
      'end_size'     => 2,
      'mid_size'     => 1,
      'prev_next'    => true,
      'prev_text'    => '<b>-</b>',
      'next_text'    => '<b>+</b>',
      'add_args'     => false,
      'add_fragment' => '',
    ]);

    if (is_array($entries))
    {

      ?><ul class="pagination"><?php

      foreach ($entries as $entry)
      {?>

        <li class="page-item<?=(!strpos($entry, 'current') ? '' : ' active')?>">
          <?=str_replace('page-numbers', 'page-link', $entry)?>
        </li><?php
        
      }

      ?></ul><?php

    }
  ?>
</nav>