Depending on product type, you can choose from several yarn qualities and sizes. E.g. Football scarf in acrylic in standard size, or blanket in cotton in baby size.
The combination of material and size is picked before starting the Online Designer, so right color palette and template size can be loaded. Choose product, then yarn, then size, then do your design.
Only for sweaters, choose sweater size in the Online Designer, and not upfront.