Rendering volume to fixed resolution output then rescale to window

Hello, how do I setup the volume mapper + render window (+ potential new nodes in the pipeline) to ensure I never use an output render target which is larger than a certain maximum width,height? I want to keep rendering interactive even if the final viewport is resized to large resolution on qhd monitor.

Say Volume … Target (512,512) … Final render window(2048,1024).

I would like to keep things interactive and allow things like rotating the volume and picking. If it’s already supported, all the better, otherwise I would be happy to take suggestions on which base classes to start from.