One can configure country options in Magento 2 that identifies where the business is located and the countries from where the store accepts the orders.
The store admin can restrict countries to place an order as the business may be local. Or the products offered may be restricted in some countries, or shipment may be costlier.
Refer the method to configure country options in Magento 2 to allow customers to only select the shipping to countries allowed from the country options in the backend.
