When processing an estimate, you can add services and products. Please note that when you add products to an estimate, they are not written off from the warehouse. You can write off the products from the warehouse after you convert the estimate to a work order.
Thus, thanks to the estimate, you can add all the services and products required for the work order without changing the actual state of stock levels.
Read more about how to add services and products to estimates and work orders in this article.