You have it backwards. You don’t do ECs to “show your interest”. You do ECs which allow you to engage in your interests. If Journalism interests you, find a way in which to engage in journalism.
Trying to impress colleges doesn’t impress colleges. Taking classes and doing ECs to tick off the “right” boxes is very easy to spot.
Have you been engaged in your high school’s newspaper? Have you contacted any journalists and asked them what experiences there are for high school students?
In general, for the best way to engage in any specific field or direction which interests you, you should contact people who work in those fields. Alternatively, contact professors who teach those fields in college.