To use methods such as Afterpay, Zip, Klarna, or Gem, these payment methods would need to be shown on the item's listing, as shown below.
Some of these methods have a minimum and/or maximum order limit too. For example with Afterpay, if the total of your order is over $2000.00, Afterpay cannot be used to pay for the order.
Zip is not eligible for pre-order items, so if an item is on pre-order, Zip will not be available at checkout.
You would also need to use a verified address in order to use these payment methods, and you can read more about setting that up here.