Custom registration form in wordpress theme/plugin

Friends, as you all know, WordPress has a registration form and sign up form. Register and Sign up form works as a user authentication method with the help of which any user can create his account, login and do his work easily at the address according to his role.

By default some fields are created on logo and sign up form, if we want to customize them then we can do it using these methods:

[register_form]

<?php do_action('register_form'); ?>

<?php
/*
Template Name: Registration
*/

global $current_user;
wp_get_current_user();

$firstname = $_POST['firstname'];
$lastname = $_POST['lastname'];
$company = $_POST['company'];

if (($firstname != '') && ($lastname != '') && ($company != '')) {
    // TODO: Do more rigorous validation on the submitted data

    // TODO: Generate a better login (or ask the user for it)
    $login = $firstname . $lastname;

    // TODO: Generate a better password (or ask the user for it)
    $password = '123';

    // TODO: Ask the user for an e-mail address
    $email = 'test@example.com';

    // Create the WordPress User object with the basic required information
    $user_id = wp_create_user($login, $password, $email);

    if (!$user_id || is_wp_error($user_id)) {
        // TODO: Display an error message and don't proceed.
    }
    
    $userinfo = array(
        'ID' => $user_id,
        'first_name' => $firstname,
        'last_name' => $lastname,
    );

    // Update the WordPress User object with first and last name.
    wp_update_user($userinfo);

    // Add the company as user metadata
    update_usermeta($user_id, 'company', $company);
}

if (is_user_logged_in()) : ?>

    <p>You're already logged in and have no need to create a user profile.</p>
    
<?php else : while (have_posts()) : the_post(); ?>

<div id="page-<?php the_ID(); ?>">
    <h2><?php the_title(); ?></h2>

    <div class="content">
        <?php the_content() ?>
    </div>

    <form action="<?php echo $_SERVER['REQUEST_URI'] ?>" method="post">
        <div class="firstname">
            <label for="firstname">First name:</label>
            <input name="firstname"
                    id="firstname"
                    value="<?php echo esc_attr($firstname) ?>">
        </div>
        <div class="lastname">
            <label for="lastname">Last name:</label>
            <input name="lastname"
                    id="lastname"
                    value="<?php echo esc_attr($lastname) ?>">
            </div>
            <div class="company">
            <label for="company">Company:</label>
            <input name="company"
                    id="company"
                    value="<?php echo esc_attr($company) ?>">
            </div>
    </form>
</div>
    
<?php endwhile; endif; ?>

global $current_user;
$firstname = $current_user->first_name;
$lastname = $current_user->last_name;

global $current_user;
$company = get_usermeta($current_user->id, 'company');