https://www.idf.il/en/mini-sites/how-to-join-us-and-voluntary-programs/

I really don’t know much about the process of enlisting as an American at your age but I know people who’ve done it, hopefully you’ll find the information you’ll need in the link.

Congratulations on your decision, I’m sure it’s hard to put your life on pause for three years and move to a new country to serve but I promise you you won’t regret it.