gistfile1.php

<?php

$post_ids = array( 1, 2, 3, 4 );

foreach ( $post_ids as $post_id ) {
    $post = get_post( $post_id );
    
    if ( null === $post ) {
        continue;
    }
    
    setup_postdata( $post );
    
    // ... do stuff with this post
    
    wp_reset_postdata();
}