Good design is not about higher CTRs (click-through-rates) or pageviews. It’s about delivering value to your business by serving your customers. Therefore, establish KPIs that align with the value you offer, instead of tracking superficial metrics.
One thing to remember: Defining the value-driven KPIs is not a solo job for designers. Product managers, marketing teams, and stakeholders at all levels should work together to build products/services that provide customer value to build a better business.