A delivery option can carry two discounts: the one the customer starts on, and the one that takes over after a number of payments. A common use is 20% for the first three deliveries and 10% from then on.
Expand the delivery option and tick Offer discount, then pick a Discount type and a value. The second discount lives under the same checkbox: it appears as soon as Offer discount is ticked, before you have entered a value.

Tick Change discount after specific number of payments. Three more fields appear.
Discount type for changed discount: percentage off, amount off or fixed price again. It does not have to match the first one.
Change discount after: how many payments the starting discount should last. The field takes 1 to 999 and is required once the box is ticked, so 0 fails with "Must be at least 1".
Change discount to: the value that takes over. 0 is allowed, which ends the discount entirely after those payments. The collapsed badge still shows that half, as "then 0% off after 3 payment(s)".
Collapse the option. Its badge now shows both halves. The widget preview reads differently: the starting discount shows as a Save badge, and only the "then" half becomes a chip under the option.
These subscriptions do not step: the second discount applies from the first renewal onwards, whatever number of payments you set. Only the first order, the one that goes through checkout, uses the starting discount.
Set the second discount per delivery option, so a weekly and a monthly option can ramp differently.
Check the widget preview before saving.
Stuck on any of this? Open the chat in the bottom right corner of the app and we will help you set it up.