You mean without a deployment or statefulset? How would you connect to the DB without a service providing a persistent DNS name?
these manifests can be targeted with a Service.
However my preferred solution for databases inside k8s is still zalando-operator with spilo and local storage. it's rock solid. I once used kubedb and lost the database because of bugs, so I'm staying away from them. Crunchy looks solid aswell but it looks like it's a little bit more polished but harder to configure than zalando's solution which is more built to their needs.