Hank here from Shopify!
When using a manual payment like cash on delivery (COD) within your store, you are not charged any transaction or credit card fees. The only exception to this is if you are using the Advanced cash on delivery app for merchants based in India, as you can see below.
But as the help guide suggests, if located within India, you can disable the app and use the standard COD options.
I hope this helps, but let me know if you have any further questions!
All the best,