Override checkout price per product wordpress

Hello,

We need add function for coupons to code on backend new type "Override checkout price per product"

Lets say, we have coupon value with 50 eur
We need code function for coupon type that will overide price in cart
So lets say Samsung s9 price on website will be 120 eur but user already buyed on some store coupon for 50eur (as completed price / not discount)

So now customer will add to cart this product - will use coupon ie "test" with value for this product with 50 eur so price in checkout will be override to 50 eur BUT because customer already paid for this... will pay 0 and will be status as PAID via coupon

for this doesnt exists plugin on market.. as its very specified situation...

Thanks for helping