Look at the colleges Common Data Set. It states what each college takes into account for admissions.
The more applicants a college have, the less they can be holistic, in general. So if you look at a big U like Penn State, you see ECs are considered, but are not Very Important or Important.
If you look at Harvard, you see almost everything is “considered”…no one thing is shown as more important than another.
At a LAC like Bryn Mawr, ECs are Important.