You can create a complete sales funnel and make a conditional one-time offer after checkout easily.
When a buyer completes a checkout process, trigger a WooCommerce one click upsell offer with greater value. And then follow up with a downsell offer that costs even less!!
"Once a person has completed the checkout, this is your chance to make the buyer purchase more from you using attractive upsell and downsell offers."
The concept of using Upsell offers after checkout is, when a buyer has already committed to a purchase, you can give more offers and convince him to spend even more.
If you offer the right products as upsell or downsell, most buyers will end up taking the offers, thus boosting your revenue.
"The possibility of selling to an existing customer is 50% more than when selling to a new buyer!"