Want to show feature image at the top of post

Hi all,

My posts feature image that is used to display when viewing in a category. I want to also show it at the top of the post itself.

I used this code in my single.php to achieve this:

<?php if ( has_post_thumbnail() ):?>
<div class=”featured-image-wrap”><?php the_post_thumbnail(); ?></div>
<?php endif; ?>

Now my issue is that when I put in the standard wordpress sizes they don’t work well across multiple screens. So I would like it so that the image is responsive.

I am meant to put the size between () of <?php the_post_thumbnail(); ?> but I don’t know how to do this to make it responsive

Could someone kindly help me.

Many thanks