How add specific text to specific post

hi, i would add specific text to specific posts but without admin page.
its hard to explain but i need something like that:

<?php if(in_category(‘category name’)) : ?>
Specific text
<?php endif; ?>

it add text to all posts in ‘category name’ and working great but how make changes to add text to specific post?
Something like that (Of course it did not work):

<?php if(some_posts_function(‘post title’)) : ?>
Specific text
<?php endif; ?>