Displaying the tagline

It is possible and depends on where you would like to put it. Most likely you should create a child theme and adjust line 56 in header.php to show:

<h1 class="site-title"><a href="<?php echo home_url( '/' ); ?>" title="<?php echo esc_attr( get_bloginfo( 'name', 'display' ) ); ?>" rel="home"><?php bloginfo( 'name' ); ?> | <?php bloginfo( 'description' ); ?></a></h1>

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The difference being that bloginfo(‘description’); is now added, which will echo the tagline.