You need to echo
your link:
<a href="https://wordpress.stackexchange.com/questions/54801/<?php echo esc_url( get_category_link("23') ); ?>">
<?php echo get_the_category_by_id(23); ?>
</a>
You need to echo
your link:
<a href="https://wordpress.stackexchange.com/questions/54801/<?php echo esc_url( get_category_link("23') ); ?>">
<?php echo get_the_category_by_id(23); ?>
</a>