Hello,
Checkout is the default WooCommerce option, our theme does not have any special options for this. Additional PHP customization is outside the scope of our support, unfortunately https://themeforest.net/page/item_support_policy
So, try WooCommerce Snippet https://woocommerce.com/document/change-the-default-state-and-country-on-the-checkout/ and contact WooCommerce support if that does not help https://wordpress.org/support/plugin/woocommerce/
Regards