Hi there,
the simplest method would be to add that text to the Excerpt field in the post editor. This will also be displayed in the Archive post excerpt.
Then create a hook
Add this content:
<?php if ( has_excerpt() ) : // Only show custom excerpts not autoexcerpts ?>
<p class="entry-subtitle"><?php echo get_the_excerpt(); ?></p>
<?php endif; ?>
Select after_entry_header
hook
Check Execute PHP
Set Display Rules to Posts > All Posts
Then in Customizer > Layout > Blog –> Featured Images >>> Set its location to Below Title.