There's a concept called the Overton Window, which refers to a range of opinions that are mainstream-enough to be held without being considered a kook of some sort.

These are just methods of injecting fringe ideas into mainstream discourse to make it seem like 'normal' people think these things. A lot of this just functions via repetition, see also the 'Big Lie' technique, which has a history going back quite a bit further than last November.

https://en.wikipedia.org/wiki/Overton_window

https://en.wikipedia.org/wiki/Big_lie