containerPort as part of the pod definition is only informational purposes. Ultimately if you want to expose this as a service within the cluster or node then you have to create a service.
To answer your question, yes it is enough if you just expose it as part of the Kubernetes service. It is a good practice to mention as part of the pod definition so that if someone looks at the definition can understand the port where your container service is running.
This is very well explained here
Official kubernetes reference documentation