You can template the ~/.step/config/defaults.json file with Ansible with the different redirect URL:

[jdoss@sw-0608 config]$ ll ~/.step/config/defaults.json
-rw-r--r--. 1 jdoss jdoss 253 Feb  9 19:50 /home/jdoss/.step/config/defaults.json
[jdoss@sw-0608 config]$ cat ~/.step/config/defaults.json
{
  "ca-url": "<https://ssh.joetest.ca.smallstep.com>",
  "fingerprint": "snip",
  "root": "/home/jdoss/.step/certs/root_ca.crt",
  "redirect-url": "<https://smallstep.com/app/teams/sso/success>"
}

You can create a fresh client and step ssh config --team name and then see the files it puts down initially

[jdoss@sw-0608 ~]$ tree .step/
.step/
├── certs
│   └── root_ca.crt
├── config
│   ├── defaults.json
│   └── identity.json
├── identity
│   ├── identity.crt
│   └── identity_key
└── ssh
    ├── config
    ├── includes
    └── known_hosts

We have had another customer that wants to template these per user on workstation provision which is fine but the .crt and key files are pulled down by the step ssh login. You should be fine to template at least defaults.json