How do I create a product template

Anyone can shed some light here?

Online store → Themes → Edit code → Add a new template → “Product” as product type → product.xxx.json → Done

Error: Invalid value for type in block ‘properties’. Type must be defined in schema.

karimali831_1-1716570096705.png

Thanks.

Still unable to create product template using JSON. liquid option allows me too anyone else experiencing this issue or can point me out how to get around this ?