Bulk Acknowledge Alerts

Is there any way to bulk acknowledge alerts from the command line or the web interface?

I have never seen it done in the web ui or from the cli. But you could do it from the API. https://docs.librenms.org/#API/Alerts/#ack_alert

If you have that many alerts notifications you should consider adjusting the number alerts that are sent.
By setting the Max alerts 1 per alert rule.