I would like to set a custom discount price to an existing cart/quote in my controller and found some other people that had this question but none of them got answered:
I want to add discount to existing quote using controller file Magento 2
Magento 2 : How to Set custom Discount from controller?
To give you an example, if the customer clicks a button in the cart he will get a random discount price. But now how can I achieve to add this specific disount price to the cart and quote in the controller?
