Update wp post with post ID

I'm trying to make a function that updates a post after form submission because I have uploaded a file with the form that converts the image into an URL, and then I want to make it the featured image in a post, but the post has to be manually updated to get the featured image loaded in.

Update I figured out how to get post id but still have the problem that it won't update the post. I am aware that i need some type of post array in the wp_update_post but I don't want to change anything, I just want to load the featured image. If there is a simpler way please let me know.

add_action( 'gform_after_submission_2', 'custom_action_after_apc', 10, 2 );
function custom_action_after_apc( $entry, $form ) {

    //if the Advanced Post Creation add-on is used, more than one post may be created for a form submission
    //the post ids are stored as an array in the entry meta
    $created_posts = gform_get_meta( $entry['id'], 'gravityformsadvancedpostcreation_post_id' );
    foreach ( $created_posts as $post )
    {
        $post_id = $post['post_id'];
        wp_update_post($post_id);
    }
}

I found a solution to my problem to have a featured image with the post, so if someone else has the same problem, these are the functions that worked for me.

You have to modify some field names, but that should not be a big deal.

/*
 * Plugins
 * =======
 * 
 * Gravity Forms by Gravity Forms
 * <https://wordpress.com/plugins/gravityforms>
 *
 * Advanced Post Creation Add-On By Gravity Forms
 * <https://www.gravityforms.com/add-ons/advanced-post-creation/>
 *
 * Advanced Custom Fields (ACF) by WP Engine
 * <https://wordpress.org/plugins/advanced-custom-fields/>        
 */

add_action('gform_after_submission_2', 'custom_action_after_apc', 10, 2);
// (The _2 in the gform_after_submission is the form id.)

function custom_action_after_apc($entry, $form)
{

    // If the Advanced Post Creation add-on is used, more than one post
    // may be created for a form submission.
    // The Post-IDs are stored as an array in the entry meta.
    $created_posts = gform_get_meta(
        $entry['id'],
        'gravityformsadvancedpostcreation_post_id'
    );

    foreach ($created_posts as $post) {
        $post_id = $post['post_id'];

        // Get the title and featured image URL from the form fields.
        $title = get_field('title', $post_id);
        // $title = 'nu ska vi testa';
        $featured_image_url = get_field('featured_image', $post_id);
        // $featured_image_url
        
        // Update the post-title.
        $post_data = array(
            'ID' => $post_id,
            'post_title' => $title,
        );

        wp_update_post($post_data);
        
        // No featured image to update.
        if (empty($featured_image_url)) {
            continue;
        }
        
        // Download the image and set it as the featured image.
        $image_id = custom_upload_featured_image(
            $featured_image_url, 
            $post_id
        );

        // Set the featured image for the post.
        set_post_thumbnail($post_id, $image_id);
    }
}

// Function to upload and set a featured image from a URL.
function custom_upload_featured_image($image_url, $post_id)
{
    require_once(ABSPATH . 'wp-admin/includes/file.php');
    require_once(ABSPATH . 'wp-admin/includes/media.php');
    require_once(ABSPATH . 'wp-admin/includes/image.php');

    // Upload the image from the URL.
    $attachment_id = media_sideload_image($image_url, $post_id, null, 'id');

    if (! is_wp_error($attachment_id)) {
        return $attachment_id;
    }

    return 0;
}