Custom search for shortcode only for post

fucntions.php

function cpsearchform( $form ) {
 
    $form = '<form role="search" method="get" id="searchform" action="' . home_url( '/' ) . '" >
    <div><label class="screen-reader-text" for="s">' . __('Search for:') . '</label>
    <input type="text" value="' . get_search_query() . '" name="s" id="s" />
    <input type="hidden" name="post_type" value="post" />
    <input type="submit" id="searchsubmit" class="dt-btn" value="'. esc_attr__('Search') .'" />
    </div>
    </form>';
 
    return $form;
}
 
add_shortcode('cpsearch', 'cpsearchform');

Add the code in your child theme functions.php to create a custom search form only for posts and then use the shortcode [cpsearch] to display the form