By default yes. There are two options to restrict its scope:
The –watch-namespace argument (or environment variable) restricts the controller to one namespace and one namespace only.
The kubernetes.io/ingress.class annotation allows you to indicate which configuration the controller should use. This allows you to use only a subset of ingress configuration across all namespaces. On the controller end, this is chosen using the --ingress-class argument/CONTROLLER_INGRESS_CLASS environment variable, and defaults to kong.
Note that there are some nuances to which resources require the annotation, and that resources with no annotation are always handled: Dbless: Kong ingress.class != kong doesn't work with KongConsumer type: key-auth