Personally I prefer MORE tag method as you will get the most consistent results with it – you chose the exact place where you will cut the article. With automatic excerpts sometimes you get funky results, as it counts the words (I guess the default is 25 words) where to cut the post. So if your post is very short or you have picture at the top, then you may have different outcomes.
You have to copy template-parts\content.php to your child theme and then edit it a bit:
<?php if ( is_search() ) : ?>
<?php tinyframework_excerpt(); // Function located in: inc/template-tags.php ?>
<?php else : ?>
<div class="entry-content" itemprop="articleBody">
<?php
// Functions located in: inc/template-tags.php
tinyframework_post_content();
tinyframework_post_pages_nav();
?>
</div><!-- .entry-content -->
<?php endif; ?>
and change it to:
<?php if ( is_search() ) : ?>
<?php tinyframework_excerpt(); // Function located in: inc/template-tags.php ?>
<?php else : ?>
<?php tinyframework_excerpt(); // Function located in: inc/template-tags.php ?>
<?php endif; ?>
You will also have to look at child theme’s section to fine tune the word count:
2.5 – Control the length of Excerpts (number of words).