Payment Form: Add a condition to show size when quantity is 2

so I am trying to create a purchase form.  And when the customer selects a quantity of 2 or more t-shirts I need them to be able to select different sizes for each shirt so I need the form to create multiple ‘size’ lines based on the quantity they select.  How do I do that?

Unfortunately, we cannot add a condition in your Payment Integration to show size depending on quantity.

If you want to add a product option, you can add them right away.

Please let us know if you have further questions.

Thank you.