I’m applying to Americorps NCCC and have considered Global Citizen Year. What are some others?
Also, I am not looking to work for a year. Thanks! 
Go find a job locally and earn some money to help pay for college.
The fact rhat you are specifying “free” and “low cost” indicates that money is an issue.
Get a job.
Depends on OP’s aid situation. Working may cost him money!
I want to do something like community service/travel abroad where living expenses will be covered. Also, my parents won’t let me work for a year because they’re very traditional. I’m hoping to do AmeriCorps NCCC and re-applying to some state schools to become class of 2021.
Seems like the traditional thing to do after high school is go to work or attend college.
There might be some local programs where you can get paid to do volunteering in your area, or in other areas if you want to get away from home. I’d suggest looking for them by googling “AREA” “VOLUNTEERING TOPIC OF INTEREST” “paid volunteering” or something like that.
Also, make sure you apply as early as you can, and to as many programs as you can. Getting into volunteering programs where you get money can be more difficult than getting into colleges.
Also, check this out: https://www.youthventure.org/who-we-are
They help you start and operate your own social venture.
Americorps has a stipend, but you make a time commitment. I know City Year can place you in your home area, has a stipend, and may offer a small college scholarship. Again, a time commitment. The best programs tend to be serious about you staying long enough to make a difference where you serve. A life lesson.
You can travel when your commitment ends.
I had always heard about people teaching English in China and Japan for a year. Do not know anything about it.
Americorps NCCC might give you access to Student Conservation Association internships, but not all SCA are AC-eligible, so you may want to look at the SCA site directly and look at the internships there. They vary from trail work to biological-surveys to historic building renovation to education, and vary in length. Typically offer travel and living stipend and usually a place to live (might be a tent!).
You could consider WWOOFing and have the ability to have a volunteer exchange on sustainable and organic farms and properties either in the U.S. or around the world. Transportation to and from the location is dependent on you, but your room/board/food is provided by your placement. Alsooo you could consider au pairing abroad! Denmark is a country that pays very well (min. 450 us dollars a month) and the host family is required to cover transportation back home. (So all you have to pay for is transportation to Denmark) Alsoo there is a new exchange program to China, EarlyBirdExchange that covers EVERYTHING. Roundtrip flight to China, a modest stipend, room/board/food - in exchange of practicing English with host siblings.
Paid positions for teaching English in Japan are competitive. A high school graduate with no training in ESL will not find a position that pays enough to sustain himself/herself in Japan.
He might find something in China, but would have to get there, and live there while looking for such a position. And be lucky. In South Korea, plenty Americans cobble a living after lining up a few private ESL students - but no one funds their travel or living expenses. To get a job that will actually pay your flight over and provide housing is unheard of unless you have a college degree, and proper training.
The reality is that an 18 year old has no skills that are needed badly enough in the developing world for someone to pay hundreds/thousands of dollars to bring the kiddo over and feed/house them during their volunteer stint.
Even doctors who go to the developing world to conduct life-saving surgeries are doing this on their own dime.