We can find help regarding most commands like
But can I find manuals for special characters used for operations like piping(| symbol)? If there's none, is there any official documentation on this?
No, because these special characters all belong to induvidual, different programs.
Although many of them have similar meanings, it can sometimes - at least a little bit - differ. For example,
\ has the same effect in a bash command line, as in a grep, but it escapes different things.
To get the list of the meanings of the special characters, you have to find them the corresponding manual pages (or other documentations).
As you are likely learning the Linux command line, you will most likely find special characters in
It could be useful to read also the meaning of the special characters in regular expression (google for "regexp tutorial").