Example Create Shortcode WordPress

Function.php

<?php
function custom_loop_function( $atts ) {
    ob_start();
    $opts = shortcode_atts( array(
        'type' => 'post_type_option',
    ), $atts );
    $output = '';
    $args = array(
        'post_type' => $opts['type'],
        'posts_per_page' => '10',
        'order' => 'DESC',
    );
    $loop = new  WP_Query( $args );
    while ( $loop->have_posts() ) : $loop->the_post();
        $id = get_the_ID();
        $title = get_the_title();
        $image = get_the_post_thumbnail($id,'full');
        $excerpt = get_the_excerpt();
        $link = get_permalink ();
        $content = get_the_content ();

		?>
            <div>HTML Content</div>
        <?php

    endwhile;
    wp_reset_postdata();
    return ob_get_clean();
}
add_shortcode('custom_loop_shortcode', 'custom_loop_function');