Adding extra line in title

Hi folks, I need help adding an extra line in my title. I need the second line to appear smaller than the previous line above it i.e. I want the second title line to represent some sort of a tag line with <h2> or <h3>. Here’s what the code looks like:

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<header id=”masthead” class=”site-header” role=”banner”>

<div class=”hgroup full-container”>
” title=”<?php echo esc_attr( get_bloginfo( ‘
‘,’name’, ‘display’ ) ); ?>” rel=”home” class=”logo”><?php vantage_display_logo(); ?>

<?php if( is_active_sidebar(‘sidebar-header’) ) : ?>

<div id=”header-sidebar”>
<?php
// Display the header area sidebar, and tell mobile navigation that we can use menus in here
add_filter(‘siteorigin_mobilenav_is_valid’, ‘__return_true’);
dynamic_sidebar( ‘sidebar-header’ );
remove_filter(‘siteorigin_mobilenav_is_valid’, ‘__return_true’);
?>
</div>

<?php else : ?>

<div class=”support-text”>
<?php do_action(‘vantage_support_text’); ?>
</div>

<?php endif; ?>

</div><!– .hgroup.full-container –>

<?php get_template_part( ‘parts/menu’, apply_filters( ‘vantage_menu_type’, siteorigin_setting( ‘layout_menu’ ) ) ); ?>

</header><!– #masthead .site-header –>
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Any advice is greatly appreciated!
Thanks