With vROps webhooks - see this blog post for details: https://blogs.vmware.com/management/2022/01/use-vrealize-operations-to-monitor-the-load-on-the-web-tier-and-kick-off-the-automation-to-scale-the-tier-in-or-out-by-adding-or-removing-web-nodes.html#MIT#vROPackage#vRealizeAutomation#vRealizeOperationsManager