Create event relay

POST {{_endpoint}}/services/data/v{{version}}/tooling/sobjects/EventRelayConfig/

Request Body

{"FullName"=>"MyEventRelay", "Metadata"=>{"eventChannel"=>"Carbon_Comparison_Channel__chn", "destinationResourceName"=>"callout:MyNamedCredential", "label"=>"My Event Relay", "relayOption"=>"{\"ReplayRecovery\":\"LATEST\"}"}}