Library
Any part of your project that you can do at the library you can do there. It's free, and you might have people studying around you so in that way it is also a school-ish environment. And you're more likely to get the frickin work done if you already went through the effort to taking your work all the way there.
People will work at cafés for the same reason if you can afford it. It can be an occasional treat.
A friend's place. Having a group of friends where you all have some project going on and you meet once a week just to work you your separate stuff, that's a really good way to make sure you all progress in your work. And it's fun! You can do things like state your goal at the beginning of the session and before you all pack up and go home you all review if you reached the goal or not.
A Discord server. If you don't have access to a physical place, getting some people with projects and making a server with them. You can have daily meetings if you want, state your separate goals and deadlines, and hold each other accountable.
If it's in your budget, renting part of an art studio with other artists. Having your own work place where you do your work while having coworkers in the same place as you will certainly make you work. Obviously this is more for professionals with an income making art so it depends on where you're at I guess
Art schools can have year long project courses you can apply for. You might get your own art studio and the goal is to make your project. You'd get deadlines and have classmates working on their own projects.
An art summer camp could also be an option if you find one that lets you do your own project.