Actually, the Cart and Checkout pages are the default WooCommerce pages, and the theme does not have any influence on them except for some styling.
If you want to add some more fields or content on those pages, then you have to make it possible using Customization.
You can check this article as a reference: https://hollerwp.com/customize-woocommerce-checkout-page/
OR you can try with any third-party plugin which better meets your requirements but at your own risk.
Regards 8Themes Team.
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