The shipping settings that you use affect what your customers see at checkout.
How your customers choose a shipping option
As soon as your customers reach checkout and enter a shipping address, their shipping options are displayed. Although you can configure many options in your store's shipping settings, each customer is shown only those applicable to their order. The most inexpensive option is shown as the default:
Depending on your theme, your customers might be able to get an estimate for their delivery costs before they complete the order:
Your customers won't see their shipping options until they enter a delivery address.
If your customer leaves the checkout page to change the contents of their order, then their shipping rates might change. Since most shipping rates are calculated based on an order's weight, any significant changes to its contents can make the original shipping rate inaccurate. When your customer returns to the checkout process after changing their order, they're redirected back to the same step of the checkout process. They won't receive the new, recalculated shipping rate until they're ready to complete their purchase.
Checking out with PayPal Express
If your customers are checking out using PayPal Express, they are first taken to the PayPal page to enter their credit card information and billing address. After this step, they’re shown available shipping options.
You might want to inform your customers that they will encounter this intermediate step if they’re using PayPal Express. An easy way to do this is to create an information page and link it to the footer of your store.
Unavailable delivery addresses
Customers who enter a shipping address in a region that isn't included in your shipping zones receive a notice that there is no shipping rate available for their region.