Hi Cardencbd,
Per this FAQ from Square Support:
On Square Online, coupons can’t be used with discounts. If your customer adds a discounted item to their cart, they won’t be able to add a coupon at checkout. However, on your Square Point of Sale, coupons can be combined with discounts in the order that gives your customer the best value.
You can submit a Feature Request here for future consideration. If there's enough demand for this option (meaning others have requested the same thing), it's possible it could be made an option - there's no guarantees but, that's the process for new ideas or suggestions.
