How do I enter a description when adding a custom item when I create an order for a customer?

[molemansd1]

I have the Craft theme. I enter a lot of orders directly for my clients that call them in to us. We do a lot of custom pastries and cakes outside of our normal product catalog. We would like to enter a detailed description when adding a custom item to an order or draft we create. How can I do this without an app? This is a standard thing in Wix but can't seem to do it in Shopify. See attached image as an example.