Approve additional file download when the customer chooses an additional option

Hello, I need to add a functionality for selling downloadable products, so that when the customer chooses an additional option at the time of purchase, he will receive an additional file in addition to the file he will receive from the product.
Example: I am selling a product that is the design of a house, then I will add an additional option for the customer to choose if he wants to buy an additional one: interior design.
If the customer buys only the house project, he only receives the house project file, but if he chooses the additional one: interior design, he also receives the interior design file.