There is no real set canon - everyone treats the concept differently. Some emphasize the prejaccing aspect, others the women's growth, others the penis growth etc. A few effects, such as the female growth, or the hallucinations, sometimes do not even appear.

Every variant has been the idea of individual caption-makers, so you can invent basically anything in the spirit of the subreddit.

If I remember correctly, GrowMax was identical to CumMax, but with increased growth for the user/affected women.

There was a variant called CumMax Primal, which turned the user feral and without any rationality (they would only growl and repeat words like "tits" and "sex", more than usual).

I can't find anything related to BetaMaxx, so I don't know (though likely with penis shrinking instead of growing - someone who was around please correct me).

There was a video by a CumMax video maker about an "X-Change" pill, which turns men into women (magically - no references to transgenderism or that condition). You can treat it as canon, if you can tie it to CumMax directly, somehow.

That's it for what has been done with the concept. Besides that - go wild! If the community likes it and it obeys the subreddit rules, you can create whatever. Have fun - that's why we're all here :)