Display related post instead of recent post - php

Question

I am trying to figure out a Jupiter theme blog > components > blog-similar-posts.php code. I would like to show Related Posts instead of Recent Posts on the blog pages. What should I change in the following codes?
Here is the original code I have, thanks! I think I couldn't figure out the logistic between the $recent and $related. There might be something I changed wrong during the process
<?php
global $post, $mk_options;
if ($mk_options['enable_single_related_posts'] == 'true' && get_post_meta($post->ID, '_disable_related_posts', true) != 'false') :
$backup = $post;
$tags = wp_get_post_tags($post->ID);
$tagIDs = array();
$related_post_found = false;
$layout = get_post_meta($post->ID, '_layout', true);
$layout = !empty($layout) ? $layout : 'full';
$layout = ($layout == 'default') ? $mk_options['single_layout'] : $layout;
if ($layout == 'full') {
$showposts = 3; /* 4 before */
$width = ($mk_options['grid_width'] / 3 /* 4 before */) - 30;
$height = ($mk_options['grid_width'] / 3 /* 4 before */) - 80;
$column_css = 'three-cols' /* four-cols before */;
}
else {
$showposts = 3;
$width = (($mk_options['content_width'] / 100) * $mk_options['grid_width']) / 3;
$height = ((($mk_options['content_width'] / 100) * $mk_options['grid_width']) / 3) - 40;
$column_css = 'three-cols';
}
if (!function_exists('mk_similar_posts_html')) {
function mk_similar_posts_html($title, $width, $height, $column_css, $query) {
$output = '<section class="blog-similar-posts">';
$output.= '<div class="similar-post-title">' . esc_html( $title ) . '</div>';
$output.= '<ul class="' . esc_attr( $column_css ) . '">';
while ($query->have_posts()) {
$query->the_post();
$output.= '<li><div class="similar-post-holder">';
$output.= '<a class="mk-similiar-thumbnail" href="' . esc_url( get_permalink() ) . '" title="' . the_title_attribute(array('echo' => false)) . '">';
if ( class_exists( 'Jupiter_Donut' ) ) {
$image_src = Mk_Image_Resize::resize_by_id_adaptive( get_post_thumbnail_id(), 'crop', $width, $height, $crop = true, $dummy = true);
$output.= '<img src="' . $image_src['dummy'] . '" ' . $image_src['data-set'] . ' alt="' . the_title_attribute(array('echo' => false)) . '" />';
}
$output.= '<div class="image-hover-overlay"></div></a>';
$output.= '' . get_the_title() . '';
$output.= '</div></li>';
}
$output.= '</ul>';
$output.= '<div class="clearboth"></div></section>';
echo $output;
}
}
if ($tags) {
$tagcount = count($tags);
for ($i = 0; $i < $tagcount; $i++) {
$tagIDs[$i] = $tags[$i]->term_id;
}
$related = new WP_Query(array(
'tag__in' => $tagIDs,
'post__not_in' => array(
$post->ID
) ,
'showposts' => $showposts,
'ignore_sticky_posts' => 1
));
$output = '';
if ($related->have_posts()) {
$related_post_found = true;
mk_similar_posts_html( esc_html__( 'Recommended Posts', 'mk_framework' ) , $width, $height, $column_css, $related);
}
$post = $backup;
}
if (!$related_post_found) {
$recent = new WP_Query(array(
'showposts' => $showposts,
'nopaging' => 0,
'post__not_in' => array(
$post->ID
),
'post_status' => 'publish',
'ignore_sticky_posts' => 1
));
$output = '';
if ($recent->have_posts()) {
$related_post_found = true;
mk_similar_posts_html( esc_html__( 'Recent Posts', 'mk_framework' ) , $width, $height, $column_css, $recent );
}
}
wp_reset_postdata();
echo $output;
endif;