In the spec.http.service.spec section, you can change the Kubernetes service used to expose Elasticsearch:

spec:
  http:
    service:
      spec:
        type: LoadBalancer

Check the Kubernetes Publishing Services (ServiceTypes) that are currently available.

You can add an IP or a DNS name in the SAN of the self-signed certificate configured by default to secure the HTTP layer with TLS in the spec.http.tls.selfSignedCertificate section.

spec:
  http:
    tls:
      selfSignedCertificate:
        subjectAltNames:
        - ip: 1.2.3.4
        - dns: hulk.example.com