Determine file size (Liquid?)

I’m generating my own RSS feed and there’s an element that wants to know the size of a file. Some people say to just put a “1” in there and others recommend the average or the actual file size.

Here’s my question: if I know a file name, like a podcast audio file link, can I use Jekyll/Liquid to get the file’s size?

From my research, this does not look possible but I am curious.

Thanks!

I regularly use a plugin file-last-modified.rb
https://github.com/michaelx/jekyll-last-modified
to read a file’s modification date ( mtime ) via a Ruby call. I’m sure this could be modified to return the file size.
Best, Michael