You want to verify quality with experience in process and test methods. Understanding the design requirements or specifications and what are the boundaries to failure are key to identifying quality issues.
You don't have to know how to design, but rather how to find design / process related weaknesses for deviation and failure by comparison with requirements. (specs)
Deviation is measure by Cpk >>1 and failure can be measured by HALT or testing to failure with any environmental stress which can be many simultaneously including accelerated aging.
Design knowledge comes with experience to compare best practices , failure analysis and competitor comparisons.