curl --request POST \
  --url https://{operatorDomain}/v1/admin/quotes/quote-versions/{id}/lines \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "id": "qvln_01h...",
  "quoteVersionId": "<string>",
  "description": "<string>",
  "quantity": 123,
  "unitAmount": 123
}
'

{
  "id": "qvln_01h...",
  "quoteVersionId": "<string>",
  "description": "<string>",
  "quantity": 123,
  "unitAmount": 123
}