Update cart price on selection of option

[Mairabk]

I am trying to display options through theme-app-extension in cart page. I want to give option to customer to select a dropdown value. For first option no amount is added. For second 2$ is added multiplied by total quantity and similarly 4$ for 3rd option.

I need a boilerplate code to run api call in app using current cart session and updating product price from backend

[vijaya2]

same doubt have found the solution