customer should add a picture when ordering a product

It is a product that requires an image. The customer should attach this to the order.

While this is not a built-in option, you can make use of Product Add-Ons to achieve this. You can read more about the extension at Product Add-Ons – Documentation.

For any pre-sales questions on that, please open a support request in https://woocommerce.com/contact-us/#sales-form

thank you!