I have a question I am uncertain about, but I can't find Writing SE's sandbox. I might be blind, but it seems to be in no logical place, because it should be easily accessible due to it being a great tool for new members.
So where is it or how do I access it? And please don't redirect me to Writing Meta because this question applies to all sites, since all SE sites have a sandbox.
Not all sites have sandboxes. Sandboxes are created by the community when they see a need (and hopefully have the ability to moderate one). See for example the discussion here on creating a sandbox.
I can think of a few that have "content review" sandboxes (almost always for questions):
On some sites, people are willing to give feedback in chat or on meta (where you would just post a question with the content of your proposed question, and clearly label it as a request for feedback). For example, this is the policy for RPG SE, which has the [workshop-question] tag for this.
If any of these sandboxes has been protected, someone will probably unprotect it if you either flag or ask in chat. It’s also good to note that some sites allow you to post on their metas at 1 rep; Code Golf and Worldbuilding are among them.
There are countless others that have formatting sandboxes, but it would be inappropriate to ask for anything (other than maybe formatting help) in those. I might as well make a list of those I know:
Some of these are dedicated to a specific purpose, such as testing Mathjax (but whether anyone enforces it is another story). On the flip side, remember that MathJax is only enabled on certain meta sites.
