Some schools allow a resume - so in that case it’s not a problem. But don’t force one in.
You can find a way to write, re-write, and re-write your activities some more in order to get them to the 150 - you simply need to ensure it conveys what you did.
No 18 year old’s resume should be more than a page - and no, not 9 font. I’m mid 50s and my resume is one page. You are one of many they are evaluating so they’re not going to give you an extra 5 minutes. When I get a two page resume - and I know I’m hard core -but the 2nd page goes in the trash. If you can’t convey yourself up front, you’re not right for me - and I know others who do similarly.
Good luck.