How to make the post summary taller?

You can either manually enter content into the_excerpt section or use this code in your functions.php file in your theme

function custom_excerpt_length( $length ) {
return 200;
}
add_filter( 'excerpt_length', 'custom_excerpt_length', 999 );

Change the number 200 to the number of characters you want until it’s the number of lines you’re looking for.