Web Chat throughput limits during load test

Is it possible to increase the concurrent session limit for Web Chat? Running JMeter scripts with 200 active chats hits a hard ceiling. The architect flow stalls, and the client SDK throws this error:

{"code": 429, "message": "Rate limit exceeded"}

The API calls for message history return 200, but new sessions fail to establish. Standard admin settings do not show a throttle override. Need to validate capacity before production launch.