Vivid does not make your display do anything it’s not supposed to do. Vivid enables the extra brightness range usually reserved for HDR content, in exactly the same as if you were editing HDR video. The official word from Apple on this topic is here. Apple claims the following:
"1000 nits of brightness. Pro Display XDR can sustain 1000 nits of brightness across the full screen. This means that a pro can edit an HDR photograph or video with the entire frame at 1000 nits of brightness, indefinitely."
Vivid does not use low level display hacks to push your display to levels it shouldn't go. The temperature of your displays will increase if you use your display in a very warm environment, but macOS will limit the max brightness if necessary.