According to the official documentation, the helm init command has been removed without replacement:
The helm init command has been removed. It performed two primary functions. First, it installed Tiller. This is no longer needed. Second, it setup directories and repositories where Helm configuration lived. This is now automated. If the directory is not present it will be created.
There has been another notable change, which might trouble you next:
The
stablerepository is no longer added by default. This repository will be deprecated during the life of Helm v3 and we are now moving to a distributed model of repositories that can be searched by the Helm Hub.
However, according to the official quickstart guide, this can be done manually if desired:
$ helm repo add stable https://charts.helm.sh/stable
$ helm repo update
⎈ Happy Helming!⎈