How many upsell products are shown, and can I limit the number?

Use Products to show in Plugins → Up / Cross Sell. Set it on the Upsell tab for product pages and on the Cross-sell tab for the cart.

• Enter the maximum number to show, for example 4.
• 0 shows all of them.

Click Save Upsell or Save Cross-sell. If you placed the block as a builder block in your product template, that block can override the number on its own.