Well, there's no such possibility on StackExchange. Every post is limited to 30kB of text, and a bunch of figures, if you wish.
Why? Well, there's couple reasons (most of them were already summarized in the comments):
StackExchange can't host large files. Once you allow them, there's be a large lot of them, and that's at least very expensive.
Users aren't willing to download untrusted contents. And they shouldn't be. It's not an issue with LaTeX that much, it's quite difficult to demage a computer from within a LaTeX file, but SE often deals with languages where
cat /dev/random | dd > SOMETHING can damage your computer within milliseconds. It's easy to eye-verify a short piece of code, but not large files.
There's very hardly a question that can't be stated within 30kB. In LaTeX, most problems are of the form: "I don't know how to do XYZ," or: "Using
\foo causes an error." Very likely, your question fits into one of these cases. The only necessary thing is to follow the steps in minimal working example (MWE) FAQ and invest your own time into analyzing the problem before asking others to go through large bunches of your code.
There are places where you can upload a file. The more creditted are e.g. Google Drive or Dropbox; for source code, GitHub can be handy, too.
In case you need to provide a 3rd party file. It happens that for instance a university thesis class is troublesome. In that case, it's probably accessible from the university's webpages, so simply link it.
(Marked CW since it contains a summary of suggestions by several people.)