How can I structure an IAM policy document for granting specific permissions for an IAM user or even group?

In the context of AWS, to achieve this particular objective, you would first need to create an IAM policy document with the required permissions. Here is the example given by using AWS Identity and accessing management policy JSON syntax:-

{
  “Version”: “2012-10-17”,
  “Statement”: [
    {
      “Effect”: “Allow”,
      “Action”: [
        “s3:GetObject”,
        “s3:ListBucket”
      ],
      “Resource”: [
        “arn:aws:s3:::your_bucket_name”,
        “arn:aws:s3:::your_bucket_name/*”
      ]
    },
    {
      “Effect”: “Allow”,
      “Action”: [
        “dynamodb:PutItem”,
        “dynamodb:GetItem”,
        “dynamodb:UpdateItem”,
        “dynamodb:Scan”,
        “dynamodb:Query”
      ],
      “Resource”: “arn:aws:dynamodb:your_region:your_account_id:table/your_table_name”
    }
  ]
}

You can replace placeholders such as ‘your bucket name’, ‘your region’, ‘your account id’ and ‘your table name’ with your real AWS resources name.