StoreHippo allows you to provide multiple payment methods including Cash on Delivery, payment gateways, offline payments etc.
Sometimes, you want Cash on Delivery option to be provided to specific products only, in that case Product based COD app could help you. You can install this app from Advance settings-> apps.
After installing go to the products section and edit any product. You will see a checkbox "Product based COD" in the general tab of product.
Check the checkbox if you want this product to be sold on Cash on delivery, if it is unchecked then user cannot purchase this product on Cash on delivery.
Note: You can also manage which all products are available on COD in bulk through CSV, once the app is installed you can export the product data, and search for a column "metafields.sell_with_cod", if the product is available on COD mention 1 else mention 0. After making the changes reimport the product CSV.