Yes, it is possible to create a lifecycle policy to transition specific objects within the temp/ folder to the Standard-IA storage class based on their object names. You can use a prefix filter in your S3 Lifecycle configuration to achieve this.

To target objects whose names start with "template-" within the "temp/" folder, you would use the prefix "temp/template-" in your lifecycle rule. This prefix will match objects like "temp/template-file1" and "temp/template-xyz" as you described.

Here's how you can set up such a rule:

1. In your S3 Lifecycle configuration, create a new rule.
2. For the rule scope, choose to limit the scope using filters.
3. Add a prefix filter with the value "temp/template-".
4. Set up the transition action to move objects to the Standard-IA storage class after the desired number of days (remember, objects must be at least 30 days old before transitioning to Standard-IA).

This approach allows you to target specific objects within the temp/ folder without relying on tags. The rule will apply to all objects that match the specified prefix, allowing you to manage the lifecycle of these particular objects separately from others in the bucket.

Keep in mind that there's a minimum storage duration of 30 days for objects before they can be transitioned to Standard-IA. Also, objects smaller than 128 KB are not transitioned by default, but you can modify this behavior if needed.

By using this prefix-based filter in your lifecycle rule, you can effectively manage the storage class transitions for your specific template files within the temp/ folder.
Sources
Setting an S3 Lifecycle configuration on a bucket - Amazon Simple Storage Service
Transitioning objects using Amazon S3 Lifecycle - Amazon Simple Storage Service
Examples of S3 Lifecycle configurations - Amazon Simple Storage Service