How is the array of added goods in the Bitrix cart formed?

Question

1C-Bitrix

Hello, I would like to make a small constructor in the product card.

1. These are properties for trade offers
2. These are additional properties for the catalog product itself. (Creating each additional property of a product as a trade offer is meaningless, it would turn out more than 1000 trade offers for one product)
All properties affect the price in the end. Only the properties of trade offers get into the basket, so I wanted to know how the array is formed in order to add an additional property selected by the user to it.