In Magento administration, Related, Upsell, and Cross-sell products can be set for each individual product.
Related and Upsell products are displayed on the product page of those products for which we have set them up. There is no limit to their number, so if an online store administrator enters a larger number of products, all of them can be shown on the page.
On the other hand, Cross-sell products are shown in the cart according to the products that are in it. By default, they are limited to four.