Hello fam!

Check what are the KPI's that YouTube uses.

And how KPI metrics is done in ux.

Definition of KPI: KPIs (or key performance indicators) enable the measurement and monitoring of specific elements within the user experience. This furnishes tangible data, offering valuable insights into the general well-being of your product's UX and linking it to broader business objectives.

For more information check this link below.

Thank You!