The term exists and it is called the Overton Window. It has been an intentional tactic and it is happening across several political spectra. For example, being

The term exists and it is called the Overton Window. It has been an intentional tactic and it is happening across several political spectra. For example, being against illegal immigration now gets you labelled anti-immigration. Wanting the police to be held accountable for their actions is now considered leftist instead of normal. Being anti-vax is considered a personal choice worthy of consideration instead of a fringe/lunatic view. I would be very happy if I were Russia/China.