It very much depends on the school and how exemplary you are in those activities.
I would say in 90% of cases, extra-curricular activities can be as much as 1/3 or as little as about 1/10th of your application’s weight.
I would say they account for more in occasions where a student is a star athlete, being recruited for those purposes. Or if a student is a prodigy, celebrity, or tied to someone who is a donor, then those extra-curricular standings could play a very significant part in admissions.
On the other end of the spectrum, there are schools that are very low in selectivity. These schools do not admit based on extracurriculars. They have a more formulaic: score + GPA + personal statement equation.
