I wonder if Harris should support full Cannabis legalization. I lean towards yes. Ethically I'm in favor, though I haven't smoked in 19 years(how time flies)
Benefits: big with young, childless single men, a demographic less concerned with abortion, the focus of her present policy-related rhetoric. Some testosterone-filled supporters would be good, too, especially in red states and rural areas, where conservatives tend to dominate conversations at the ground level.
Disadvantages: it would piss off the traditionalists and right leaning moralists... they weren't gonna vote for her anyway. I suppose it may give Trump some rhetorical angles? I think she's avoiding controversy presently, to avoid interrupting the positive news feedback loop. That will inevitably end, which would be the time to announce support.
It's overall had the support of something like 60-65% of Americans for the past few years, with overwhelming support among Democrats, strong support among Independents, and even among Republicans, a fairly significant minority.
Overall it would probably be to her benefit because the people who would refuse to vote for her over this are already not voting for her for other reasons, but there might be some who'd be more motivated to turn out if she promised to do this.