Connection limit on istio-envoy

Is there a limit to the number of connections that envoy can handle?

Is so, what is (how / from where can one read it) and how can it be configured?

Circuit breakers — envoy 1.17.0-dev-172a39 documentation - Gives information about the circuit breaker thresholds that control max connections to an upstream cluster

We are not explicitly applying any CircuitBreaker resource. Can these be set to DestinationRule instead?