multiple post into single page

As far I understood you need to show those pages content through that query. So you can modify your code like below-

<?php
get_header(); ?>

<div id="primary" class="site-content">
    <div id="content" role="main">

        <?php
        $args = array(
            'post_type' => 'page',
            'post__in' => array( 2770, 10, 266, 1558 ) //list of page_ids
        );
        $page_query = new WP_Query( $args );
        if( $page_query->have_posts() ) : ?>
            <div class="pages-on-page">
            <?php
            //print any general title or any header here//
            while( $page_query->have_posts() ) : $page_query->the_post(); ?>
                <div>
                    <h2><?php the_title(); ?></h2>
                    <?php the_content(); ?>
                </div>
            </div>
        <?php
            endwhile;
            echo '</div>';
        else:

        endif;
        wp_reset_postdata();
        ?>

    </div><!-- #content -->
</div><!-- #primary -->

Hope that helps.