policy.json

{
  "Action": [
    "sagemaker:CreateApp"
  ],
  "Resource": [
    "*"
  ],
  "Effect": "Deny",
  "Sid": "BlockSagemakerOtherThanT3",
  "Condition": {
    "ForAnyValue:StringNotLike": {
      "sagemaker:InstanceTypes": [
        "ml.t3.medium",
        "ml.t3.xlarge",
        "system",
        "default"
      ]
    }
  }
}