How to temporarily set the featured image for a post when the post is loaded

The post_thumbnail_html action hook will be the one you’re looking for. This allows you to add conditional logic to change the source url depending on the page you’re looking at.

function new_post_thumbnail_html( $html, $post_id, $post_thumbnail_id, $size, $attr ) {
    $new_html = $html;
    if ( is_archive() ) :
         $new_html="<img src="https://your-image-source.com" alt="Your image alt tag">";
    endif;
    return $new_html;
}
add_action( 'post_thumbnail_html', 'new_post_thumbnail_html', 10, 5 );

Depending on how Elementor treats the featured image for your hero section, it may do a has_post_thumbnail() check before displaying the featured image. In that case, this solution will not work, and you might try this solution instead.