Agree with the other posts. Keep your descriptions of your ECs simple, and don’t use the resume as an “out” to contain lengthy descriptions that aren’t possible on the Common App. The common app is designed the way it is - including the limited amount of space for ECs - because that’s what colleges want. If they wanted read through lengthy descriptions of activities, then the common app would include more space for that.
Also agree with @tsbna44 about keeping your resume to one-page. Many professionals with decades of experience have a one-page resume - high school students can definitely keep it to a page.