curl --request POST \
  --url https://api.heygen.com/v3/video-agents/{session_id} \
  --header 'Content-Type: application/json' \
  --header 'x-api-key: <api-key>' \
  --data '
{
  "message": "<string>",
  "avatar_id": "<string>",
  "voice_id": "<string>",
  "brand_kit_id": "<string>",
  "files": [
    {
      "type": "<string>",
      "url": "<string>"
    }
  ]
}
'

{
  "data": {
    "session_id": "<string>",
    "run_id": "<string>",
    "title": "<string>"
  }
}