No broad community is required to be safe space. This s good, because things that are called safe space often feel unsafe to some people. That said, there are places formally or informally designated as safe space. Beyond that, Don't Be A Dick is excellent advice in general.
I choose to make my little corner of cyberspace reasonably safe. I don't let my audience pick on each other. If I'm critiquing someone's writing, I try to be decent about it. If I'm criticizing people I find troublesome, I don't punch down; but when I'm punching up, I can be pretty harsh at times, because sometimes the emperor has no clothes. I don't tolerate trolls. I tackle some big questions, both in fanfic and original writing. I try to give people an idea about content that may be upsetting to some readers, because I write about some extremely intense topics -- this week, I posted a poem about a drag racer wrecking his car, and the links included a technical article on overpass pier failures after collisions with graphic photos. Not really the kind of thing I want my fans to stumble into by accident. Conversely, I don't feel required to dumb down or nerf what I write just because some people might not enjoy reading that. It's under a cut tag and has content notes for a reason. That's so everyone can pick and choose what they want to read, or not. And I have found that this approach inclines my fans to feel safe enough to read things that are on very thin ice for them, and to discuss very difficult topics in civil ways.
Well...
I choose to make my little corner of cyberspace reasonably safe. I don't let my audience pick on each other. If I'm critiquing someone's writing, I try to be decent about it. If I'm criticizing people I find troublesome, I don't punch down; but when I'm punching up, I can be pretty harsh at times, because sometimes the emperor has no clothes. I don't tolerate trolls. I tackle some big questions, both in fanfic and original writing. I try to give people an idea about content that may be upsetting to some readers, because I write about some extremely intense topics -- this week, I posted a poem about a drag racer wrecking his car, and the links included a technical article on overpass pier failures after collisions with graphic photos. Not really the kind of thing I want my fans to stumble into by accident. Conversely, I don't feel required to dumb down or nerf what I write just because some people might not enjoy reading that. It's under a cut tag and has content notes for a reason. That's so everyone can pick and choose what they want to read, or not. And I have found that this approach inclines my fans to feel safe enough to read things that are on very thin ice for them, and to discuss very difficult topics in civil ways.
Other people's mileage may vary.