curl --request GET \
  --url https://xbt-mainnet.gomaestro-api.org/v0/rpc/mempool/transactions/{tx_hash}/descendants \
  --header 'api-key: <api-key>'

{
  "data": [
    "<string>"
  ],
  "last_updated": {
    "block_hash": "<string>",
    "block_height": 123
  }
}