how to display a page before the home page

1) create one template page on your page-templates dir in landingpage.php with this code

page-templates/landingpage.php

<?php
/**
 * Template Name: Landing page
 */
?>
<div id="main-content" class="main-content">

    <div id="primary" class="content-area">
        <div id="content" class="site-content" role="main">
                    <?php
                // Start the Loop.
                while ( have_posts() ) : the_post();
                                    the_content();
                                endwhile;
            ?>
                </div><!-- #content -->
    </div><!-- #primary -->
</div><!-- #main-content -->

2) Add your page content with image and apply link who display on click

enter image description here