Power BI consultants enable businesses to manage large datasets by designing optimized data models that balance performance and scalability. They use techniques like incremental refresh and aggregations to reduce processing times. DirectQuery or Hybrid models are implemented for real-time data access without fully importing datasets. Power BI consulting structure data using star schemas and minimize redundancy to enhance efficiency. They also leverage Power BI Premium to handle large-scale data operations. By employing these methods, consultants ensure that businesses can analyze and derive insights from extensive datasets without compromising performance.