Contact Form 7 Scripts and Stylesheet files only add if shortcode present in the page else remove it.

functions.php

function rjs_lwp_contactform_css_js() {
    global $post;
    if( is_a( $post, 'WP_Post' ) && has_shortcode( $post->post_content, 'contact-form-7') ) {
        wp_enqueue_script('contact-form-7');
         wp_enqueue_style('contact-form-7');

    }else{
        wp_dequeue_script( 'contact-form-7' );
        wp_dequeue_style( 'contact-form-7' );
    }
}
add_action( 'wp_enqueue_scripts', 'rjs_lwp_contactform_css_js');

This is nice, but what if the shortcode is contained in a widget or a related post? (some themes put the header/footer in a different post type that is linked to the page post)

This is nice, but what if the shortcode is contained in a widget or a related post? (some themes put the header/footer in a different post type that is linked to the page post)

Thanks for your comment. This won't work in your case if the shortcode present in the footer or widget the above function is only for the post content.