If you want the ability to stretch and resize a video window, have multiple video sources playing simultaneously on the video wall, switch from a single large picture to many smaller sized pictures then you will need a video wall processor that can set the window arrays into different variations and positions.
Most control rooms use a multi window processor(s) because they have multiple sources (computer data, streaming video, CCTV, broadcast, surveillance, 3D) of visual information they need to view and monitor real time. Knowing what source you want to view and display will determine what type of processor or scaler you will need and how to format it.