Shopify can use {{ localization.country.iso_code }} to determine the country from which the user is accessing the site. You can easily test the display by selecting "Country" in the store preview function.
Shopify is known for its strengths in cross-border e-commerce, but Liquid also has a wide range of tags that can be used. You can use {{ http://localization.country.iso_code }} to determine the country of origin, but you can also specify the country displayed in the preview, which is useful for display testing.