3 x 3 grid of posts on the home page

The easiest way to achieve this would be to use a custom post type. This way, these posts won’t show up as custom post types by default are excluded from the main query.

You can just then create your page and create a custom query with WP_Query to pull in this 9 posts

1. CREATE CUSTOM POST TYPE

add_action( 'init', 'create_post_type' );
function create_post_type() {
    register_post_type( 'acme_product',
        array(
            'labels' => array(
                'name' => __( 'Products' ),
                'singular_name' => __( 'Product' )
            ),
        'public' => true,
        'has_archive' => true,
        )
    );
} 

2. CREATE YOUR CUSTOM QUERY

<?php

// The Query
$args = array(
  'post_type' => 'acme_product',
  'posts_per_page' => 9
);
$the_query = new WP_Query( $args );

// The Loop
if ( $the_query->have_posts() ) {
    echo '<ul>';
    while ( $the_query->have_posts() ) {
        $the_query->the_post();
        echo '<li>' . get_the_title() . '</li>';
    }
    echo '</ul>';
} else {
    // no posts found
}
/* Restore original Post Data */
wp_reset_postdata();

All you have to do know is setup your page template, set it as front page and add your 9 posts

I hope this helps