AWS Automation Document Run Steps Against Different Servers Targeted By Tag
The issues were a lot, but the main one was not using Targets properly and then some YAML syntax problems.

---
description: "Example"
schemaVersion: "0.3"
assumeRole: "arn:aws:iam::{ID}:role/Example"
# parameters:
#   InstanceId:
#     type: "StringList"
#     description: "(Required) EC2 Instance(s) to start"
#   AutomationAssumeRole:
#     type: "String"
#     description: "(Optional) The ARN of the role that allows Automation to perform the actions on your behalf."
#     default: ""
mainSteps:
## STEP 1
- name: StartExampleServiceOnServer1
  action: aws:runCommand
  maxAttempts: 2
  inputs:
    DocumentName: AWS-RunPowerShellScript
    Targets:
    - Key: tag:Name
      Values:
      - ExampleOne-SomeService-Dev
    Parameters:
      commands:
      # Start service for SomeService
      - Start-Service -Name "ExampleOne"
      - Start-Sleep -s 30
  nextStep: ...