If you are referring to the Single Product page, then you can check out the Dashboard > Theme Settings > Single Product > Add to cart > there you can find the option to add content Before and After Add to cart: https://snipboard.io/xrYWOG.jpg
Sorry to say but right now there is no option in Theme Settings available for that. It requires Customization and this is beyond our limitations and support policy scope. Hope you can understand our limitations.
This Notice wrapper appears dynamically from WooCommerce end which is why it can’t be found under Theme files. We might suggest you to try contacting WooCommerce Support in this regard, they can guide you better on this.