Hello,
Extra content bloc is the option to add the data individually, that is why you will have to insert HTML block shortcode into each product.
If you want to insert something the same in all the products, please consider “After add to cart” area, you can find this option in the Theme Settings > Single product > Add to cart options.
One more way to add the same content to all the products is the Additional tab. The content added there would appear in all the products in a tab with the title you insert. You can find this option in the Theme Settings > Single products > Tabs.
If you have any questions please feel free to contact us.
Best Regards
.
