I have a taxonomy page taxonomoy-$slug.php
and I want to be able to display the featured image of another page on it. Is there any way to do this without plugins?
You have to place your page ID static into a variable, just like the below code:
<?php
$post_id = 12; //place here your page id
$post_thumbnail_id = get_post_thumbnail_id( $post_id );
$image = wp_get_attachment_image_src( $post_thumbnail_id ); ?>
Now, place this $image variable inside the tag:
<img src="<?php echo $image[0]; ?>" />
I hope, this may be helpful to you.