Change Posts Per Page in Archives

WordPress defaults to 10 posts per page. You can change this for all archives or a specific one. Add to your functions.php file. For more on adding pagination.

add_action( 'pre_get_posts', function( $query ) {
	if ( ! is_admin() && $query->is_main_query() && $query->is_home() ) {
		$query->set( 'posts_per_page', 12 );
	}
} );

Replace is_home() with is_archive() or is_post_type_archive('your_cpt') as needed.