How can i create a new Home page with Custom design same as template

Try once by copying all the content of ‘page.php’ or index.php. And at the top, below the <?php tag you must write the below line.
/* Template Name: My Custom Page */
But the normal wordpress loop
if(have_posts () ): while(have_posts() ) : the_post(); doesn’t work. In place of it you have to write custom query like below.

$args = array('posts_per_page'=> 20);
        $blog_post = new WP_Query($args);
        while($blog_post->have_posts() ): $blog_post->the_post();

Try it once, hope it will help you out.
Note: Child theme is recommended to customize theme.

Thanks