WordPress: Add a featured image to the blog page (more difficult than regular)

home.php

<?php 
  /****** featured image for blog page ******/
  $page_for_posts = get_option('page_for_posts'); // gets the ID of the page that displays posts

  $default_attr = array( // these are the attributes that can be passed to the image. See WP codex for all options.
      'class' => "featured-header-image",
    );
  
  global $wp_query;

  if ( $wp_query->is_posts_page && // check that we are on the posts page, and have a featured image first. Redundant.
    has_post_thumbnail( $page_for_posts ) &&
    ( $image = wp_get_attachment_image_src( get_post_thumbnail_id( $page_for_posts ), 'full' ) ) ) :
    echo "<div class='banner-image'>"; // wrap the image in html if you want to!
    echo get_the_post_thumbnail( $page_for_posts, 'full', $default_attr );
    echo "</div>";
  endif; 
  /****** end featured image for blog page ******/
  ?>