Trying to understand some concepts around Rancher/Storage formating drives

So I got rancher os installed and working on Openstack. I’m fairly new to the whole concept. But just curious…

Now say I want to launch a Kafka cluster with “decently” sized disks…

On each VM I have attached extra volumes of 150GB each.

How do you mount and format those disk?
1- Is it doable through cloud-init?
2- I assume it’s not something you want to do on cloud-init as every reboot would redo the drive?
3- And obviously don’t want to log in to each machine to do fdisk and mkfs.ext4 manually.