So the only thing I can find is that for emacs before emacs 21 it was not included (I didn't know that, I guess I installed it through my package manager or some other means back then and forgot). After that, it is included by default. But you can check to see if your package manager includes a separate `emacs-lisp-intro` or similar package. Short that, you'll have to download it from the site and install it manually to see it in emacs or just use the HTML version.

https://www.gnu.org/software/emacs/manual/eintr.html

I found it on my Mac in the menu bar. Like the one at the top of the screen next to the Apple logo. Clicking with my mouse: Help > More Manuals > Introduction to Emacs Lisp.

I assume in Windows/Linux this would actually be attached to the window frame at the top.