Use legal/borderline/not-really-legal-but-no-one’s-enforcing-it stores; Snapchat, apparently; clearweb mail order services (dumb); darknet markets; go to ‘that part of town’ and ask around.

Dunno where you are, but I found this rule held up pretty well in Canada pre-legalization- if you find the most central McDonald’s in any urban area, talk to the street kids and pretty soon you will have weed (or something that looks like weed if you’re not paying attention/acting like a douchebag). I used to include loose cigarettes and time spent chatting with street folks in the cost. That said, a) lots of risks (getting robbed, something other than weed, laced shit), and b) required talking to strangers about illicit desires. But the more rapport you build, the less likely it is you’d get burned/the more likely it is you’d get actually good shit, and get connected to a real plug.

Note ‘central’ does not necessarily mean geographically central - think about the highest foot traffic areas in town with a McDonald’s. Not suggesting you do that anyway, particularly these days.