I'm not aware of any stand-alone scope that can do this, except maybe the Windows based scopes that allow you to write your own software to run on the scope.
I'd have thought the Lecroy X-stream (Windows) scopes could do this, but although they allow a lot of math traces and can show up to eight different YT plots at the same time, they can only show a single XY plot as far as I can see. Maybe the high end Keysight or Tek scopes, but you're not likely to find them under 1k even for the older models.
So unless someone knows an affordable scope that can do this, I think your best bet is either PC based scopes, if their software supports it. I'd start by looking at
PicoScope (check the software in demo mode), and maybe also if
PulseView happens to support this, which would allow you to use a cheaper scope
supported by Sigrok/PulseView. The alternative is controlling a four channel scope (PC-based or stand-alone) from a platform like LabVIEW, MATLAB or Octave, and doing the visualization there. This will of course increase latency and reduce refresh rate.