Use Amazon S3 event notifications to trigger AWS Lambda functions directly for data transformation and loading into Elasticsearch.

Set up a cron job on an EC2 instance to periodically check S3 for new files and then trigger Lambda functions.

Manually run AWS Glue jobs to extract data from S3, transform it, and then load it into Elasticsearch.

Use Amazon SQS to queue S3 events and have Lambda functions poll the queue for processing.