Check out all the new religions that popped up, and new forms of communal living and societal organization that were being experimented with in the early 1800s in the United States:
https://en.wikipedia.org/wiki/Burned-over_district
I feel like these kinds of conversations and experiments don't really happen anymore, despite our incredible interconnectedness. Where's the global Oneida movement?
Or think about the world during early to mid 20th century, when socialist revolutions were occuring everywhere. I believe the Overton window of this era was wide enough to cause sweeping change in capitalist nations as well, such as improvements to worker's conditions. George Lucas somewhat addresses the shrinking of the Overton window in this era in an interview: https://www.youtube.com/watch?v=SWqvaMEFIdI "They never would have let me make [Star Wars] if they knew what I was doing..."
These days, organization of society as a capitalist liberal democracy is a given. It's such a given that anyone even aesthetically organized differently is automatically the world's bad guy - e.g. market-organized but still "Communist" China. Or perhaps evil Iran, with its restrictions on what women can wear (outside of Tehran) (no capitalist liberal democracy restricts women's rights at a fundamental level!!!). I haven't seen a serious conversation about alternative modes of organization outside of little bubbles of fascists or leftists.
In what ways are you seeing a wider Overton window than before? For me I think the obvious ways are surrounding mental health, minority rights, and queer lifestyles. Definitely people talk more openly in the western world about that now, and it seems much less scary now to be queer than even a few decades ago.