For the 2021 Civic LX, this
For the 2021 Civic LX, this fob feature is detailed in both the Owner's Manual and the quick reference manual. What surprised me was the distance that this works from. My testing showed that it works from at least 100 feet away and while inside a building. So, yeah, be careful with that fob. In the meanwhile, I'm going to contact my dealer and see if this can be disabled.
My story: Went to my car this morning at 8:15 to find all four windows about three-quarters down. I had parked it the previous day at about 10:30 a.m. and not used it since. My neighbor told me that when walking her dog last night at 9:00 p.m., the windows were up; otherwise, she would have noticed and told me. My guess is that I accidently dropped the windows when I put the fob in my pocket this morning. (Either that, or this is a sign that Skynet has finally gained sentience, and humankind is doomed.)
What really gets me, though, is that one has to push the fob button twice to make this happen, and hold it on the second press.