how to add a discount box in the checkout section
@THKS1
if you are Shopify Plus User then You can Customize your Checkout page.
But in Shopify basic Plan you can’t customize your Store.
I hope it will be relevant answer for this question.
Hi @THKS1
The discount field should always be available to customers during their checkout process as long as the order is eligible for a discount. Orders with automatic discounts already applied will not be eligible for additional discounts at the checkout without the use of an app.
On laptop/desktop view it should appear like this:
And on mobile it looks like this (expand the order summary to see the discount field):
