I want to show pictures in search results

It sometimes depends on the theme.
Sometimes the theme has this as a customizable feature under Customizer.

Otherwise, you can edit the content-search.php (or sometimes just search.php) file in your child theme, and output the featured image like this:
<?php
if ( has_post_thumbnail() ) { // check if the post Thumbnail
the_post_thumbnail();
} ?>

So it would look something like this:

<article id="post-<?php the_ID(); ?>" <?php post_class(); ?>>
        if ( has_post_thumbnail() ) { // check if the post Thumbnail
            the_post_thumbnail();
        }
       <header class="entry-header">
                <?php the_title( sprintf( '<h2 class="entry-title"><a href="%s" rel="bookmark">', esc_url( get_permalink() ) ), '</a></h2>' ); ?>
        </header><!-- .entry-header -->

Can you edit the file please?

<?php

$blog_full_content = nomos_get_option( 'blog_full_content', 'no' );

$width             = '1040';

$height            = '640';

?>

<?php if ( have_posts() ) : ?>

    <div class="blog-content classic">

		<?php while ( have_posts() ) : the_post(); ?>

            <article <?php post_class( 'post-item' ); ?>>

                <div class="post-info">

                    <div class="header-info">

                        <h3 class="post-title"><?php

							if ( is_sticky() && is_home() && ! is_paged() ) {

								printf( '<i class="fa fa-bookmark" aria-hidden="true"></i>', nomos_esc_text_html( '', 'nomos' ) );

							}

							?>

                            <a href="<?php the_permalink(); ?>"><?php the_title(); ?></a></h3>
							

                        <div class="nomos-post-meta">

                            <a class="nomos-post-date"

                               href="<?php the_permalink(); ?>"><span><?php echo get_the_date(); ?></span></a>

                            <span class="nomos-post-author">

                            <span><?php echo nomos_esc_text_html( 'posted by: ', 'nomos' ) ?></span>

                            <a href="<?php echo esc_url( get_author_posts_url( get_the_author_meta( 'ID' ) ) ) ?>">

                                <?php the_author() ?>

                            </a>

                        </span>

                            <div class="nomos-comment-count">

								<?php comments_number(

									nomos_esc_text_html( '0 Comments', 'nomos' ),

									nomos_esc_text_html( '1 Comment', 'nomos' ),

									nomos_esc_text_html( '% Comments', 'nomos' )

								);

								?>

                            </div>

                        </div>

                    </div>

                    <div class="nomos-footer-info">

                        <div class="nomos-cat-post">

							<?php $categories_list = get_the_category_list( ', ' );

							if ( $categories_list ) {

								printf( nomos_esc_text_html( 'Categories: %1$s', 'nomos' ), $categories_list ); // WPCS: XSS OK.

							} ?>

                        </div>

                        <div class="nomos-tag-post">

							<?php the_tags(); ?>

                        </div>

                    </div>

                </div>

            </article>

		<?php endwhile; ?>

		<?php wp_reset_postdata(); ?>

    </div>

	<?php nomos_paging_nav(); ?>

<?php else : ?>

	<?php get_template_part( 'content', 'none' ); ?>

<?php endif; ?>

Try this:
https://pastebin.com/aqm6LDRf

In this case, the image needs to come from a post type, and needs to be in the Featured Image field of your post.

Unfortunately the code does not work when I insert it I get a message
There has been a critical error on this website.

Is there a net can do this feature the appearance of images in the search
Thank you so much

You can use this php syntax checker to see there are no errors:
https://extendsclass.com/php-tester.html

that I posted here:
https://pastebin.com/aqm6LDRf

If you are throwing an error, maybe you didn’t copy and paste all the code into your file? You can see the raw code here:
https://pastebin.com/raw/aqm6LDRf

Otherwise, the theme may not have access to the the_post_thumbnail() function in WordPress. However, it is native:
https://developer.www.ads-software.com/reference/functions/the_post_thumbnail/