Yes, toggle discountable in the configuration of any of these question types.

For products, there are two special notes:

  • Products are only discountable if coupons are enabled (Configure → Payments → Coupons)
  • Products can be discountable on a product-by-product basis (defaults to on)

While you wouldn't be able to provide any discounts without coupons enabled, the first point is there in case you wonder why you can't see the toggle on products but can by default on prices and subscriptions.

General discountable toggle

Discountable price field toggle