Yeah so if you're taking anything potent you should dilute it first. A dose is like 1-3 g with 7 g onwards becoming extremely dangerous.

Like alcohol you it varies based on body mass/stomach content/fatigue/random biological factors. Like only someone with a deathwish would start a night of drinking by skulling half a bottle of vodka you absolutely should not be ingesting unknown fluids you got off some random (that are hopefully dyed to prevent confusion with water/make dosing someone's drink harder) at a dose you expect to be near heavy.

In a sane world you would get like 3 packs of 1 g doses or something with childproofing. Those doses would be diluted in a larger volume of fluid. We don't live in that world so it's about as predictable as random homebrew moonshine.

As always if someone is going to take drugs they should get them tested (cantest in the act will do it if you live there), have a sober friend, and be in a safe location.