curl --request POST \
  --url https://api.merchantops.ai/api/products/{product_key}/variants/ \
  --header 'Content-Type: application/json' \
  --data '
{
  "key": "<string>",
  "isPublished": false,
  "properties": {},
  "properties_metadata": {}
}
'

{
  "id": "<string>",
  "key": "<string>",
  "productType": {},
  "product_key": "<string>",
  "createdAt": "<string>",
  "createdBy": "<string>",
  "isPublished": false,
  "lastModifiedAt": "<string>",
  "lastModifiedBy": "<string>",
  "properties": {},
  "properties_metadata": {},
  "propertyCount": 0
}