Hey there, @Thi
Bo here from Shopify Support!
Thank you for reaching out about this, it is a great question. If the customer has left a comment in the comment box of the cart it will show up in your order under the Order Notes section here:

You may need to add further fields and options when moving forward. This can be achieved quiet easily with the help of an app.
- Product Options and Customizer allows you to add unlimited variants to your product pages: text boxes, drop down menus, checkboxes, file upload fields, swatches, calendar dates & more. This app is $18.99 per month and comes with a 14-day trial.
- Customify lets your customers customize your products so they can visualize the final product before placing an order. This app starts at $15 per month and has a 14-day free trial.
- Inkbay is a Visual product configurator to sell personalized products. Customize products that your customers can design their own with texts and images or configure by choosing parts, styles and colors. This app is $19.99 per month and comes with a 45 day free trial.
All the Best,
Bo
Bo - Social Care @ Shopify
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