The impact of aerosols on clouds in climate models remains a major uncertainty source due to the deficient representation of physical processes associated with aerosol-cloud interactions (ACI) across multiple scales. Typical horizontal resolutions for climate models (~100 km) are too coarse to explicitly resolve spatial aerosol and ACI variability. This study leverages a state-of-the-art Earth system model configured at high resolution to advance process-level understanding of aerosol and ACIs. We introduce a framework designed to assess model performance in aerosol and ACI simulations, operating at 100 km and 3 km resolutions. This framework ensures consistency in the majority of model physics across different resolutions while maintaining low computational costs through a regional refinement setup. We find that higher model resolution brings the relationship between cloud droplet number and cloud condensation nuclei concentrations to better agreement with observations, although the mean profiles of aerosol number concentration only show minor improvement at high resolution. We conclude that accurate aerosols and ACI simulations require both better-resolved large-scale cloud structures and improved representation of physical/chemical processes.