Exactly how Google measures web pages for E-A-T is unknown and unlikely to ever be.
Following their Medic update in 2018, Google incorporated the concept of E-A-T (Expertise, Authoritativeness and Trustworthiness) into their Search Quality Rater guidelines. Exactly how Google measures web pages for E-A-T is unknown and unlikely to ever be. But when creating content you want to rank make sure you know what you are talking about, can back it up and users can rely on it to make decisions.