Change number of product upsells in WooCommerce

functions.php

/**
 * Change number of upsells output
 */
add_filter( 'woocommerce_upsell_display_args', 'wc_change_number_related_products', 20 );

function wc_change_number_related_products( $args ) {
 
 $args['posts_per_page'] = 1; //change number of upsells here
 $args['columns'] = 4; //change number of columns here
 return $args;
}