Add Author Box in WordPress without Plugin - https://technumero.com/add-author-box-in-wordpress-plugin-schema-optimized/

single.php

#
# Firstly, I created a child theme.
# Now, create a single.php file in your child theme folder. I would recommend using a plugin to copy the single.php file from Parent Theme Folder to Child Theme Folder. 
# Now copy and paste the below-given code in the single.php file of your child theme, in between div tags of the post author.
#


# TN START – ADD AUTHOR BOX IN WORDPRESS WITHOUT PLUGIN 

<h4 class="about-the-author">About The Author</h4>
<div class="postauthor-wrap">
  <span itemscope itemprop="image" alt="Photo of <?php the_author_meta( 'display_name' ); ?>">
  <?php if(function_exists('get_avatar')) { echo get_avatar( get_the_author_meta('email'), '100' ); } ?>
  </span>
 
  <h5 class="vcard author" itemprop="url" rel="author">
    <a href="<?php echo esc_url( get_author_posts_url( get_the_author_meta( 'ID' ) ) ); ?>" class="fn" itemprop="name">
      <span itemprop="author" itemscope itemtype="https://schema.org/Person">
        <?php the_author_meta( 'display_name' ); ?>
      </span>
    </a>
    <span class="author-aka"> a.k.a
      <span class="author-aka-name">
        <?php echo get_the_author_meta('twitter'); ?>
      </span>
    </span>
  </h5>
  
  <?php the_author_meta('description') ?>
  
  <span class="post-author-links">
    <?php if (get_the_author_meta('facebook') != ''): ?>
    <a class="author-link f" title="Follow on Facebook" href="<?php echo get_the_author_meta('facebook'); ?>" target="_blank">
      <i class="fa fa-facebook"></i>
    </a>
    <?php endif; ?>
    <?php if (get_the_author_meta('twitter') != ''): ?>
    <a class="author-link t" title="Follow on Twitter" href="https://twitter.com/<?php echo get_the_author_meta('twitter'); ?>" target="_blank">
      <i class="fa fa-twitter"></i>
    </a>
    <?php endif; ?>
    <?php if (get_the_author_meta('googleplus') != ''): ?>
    <a class="author-link g" title="Follow on Google+" href="<?php echo get_the_author_meta('googleplus'); ?>" target="_blank">
      <i class="fa fa-google-plus"></i>
    </a>
    <?php endif; ?>
   </span>
</div>

style.css

#
# Add the following CSS code in your style.css file of your child theme. 
#

/*-Author Box---------------------------*/
.postauthor-wrap {
float: left;
width: 100%;
clear: both;
padding: 30px;
background: #fff;
box-sizing: border-box;
border-radius: 2px;
-webkit-box-shadow: 0 3px 5px 0 rgba(0,1,1,.1);
-moz-box-shadow: 0 3px 5px 0 rgba(0,1,1,.1);
box-shadow: 0 3px 5px 0 rgba(0,1,1,.1);
}
.postauthor-wrap .fn {
font-size: 24px;
}
.postauthor img {
float: right;
margin-left: 10px;
margin-right: 0px;
margin-bottom: 20px;
border-radius: 50%;
}
.author-aka {
font-size: 16px;
text-transform: lowercase;
font-weight: normal;
color: #5e5e5e;
}
.author-aka-name {
font-size: 17px;
text-transform: lowercase;
font-weight: normal;
color: #111111;
}
.post-author-links {
display: inline-block;
}
a.author-link {
background: #cc0000;
color: #fff;
width: 30px;
text-align: center;
line-height: 1;
height: 30px;
font-size: 12px;
padding: 10px 0;
box-sizing: border-box;
border-radius: 100%;
margin: 0 7px 0 0;
float: left;
}
a.author-link.f {
background: #3b5998;
}
a.author-link.t {
background: #2DA8D2;
}
a.author-link.w {
background: #e64522;
}

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