Cross sales might look insignificant for your store, but it does matter. With cross sales activated, your buyer can look up other items bought by other buyers along with the item he’d just purchased.

Here’s how to enable cross sales in your store:
1. Login to your WordPress Dashboard.
2. Go to Marketing Settings. Click Yes for Display Cross Sales.
3. You can inactivate it any time by clicking No.

And you’re done. Good luck.

*Note: Cross-sale suggestions are automatically generated from the purchase history in your store. There is not yet a way to specifically choose which products will be recommended.
Check the discussion on why cross sales might not work on your site.