Discount gives if customer opts for it

This might sound strange but my client wants that there should be a few discounts given to the customer only if he opts for it.. so is there any feature wherein we can have a button like give me the discount and only then he will get it and I want it on the cart page..

I am a developer so if you want me to modify some code I will do that too

https://www.ads-software.com/plugins/cart-deals-for-woocommerce/