Ah I see - a single multicam wouldn’t work there, but you could do it with a couple render to textures. Take the scene, and put it under a null, then parent that null under to two separate render to texture nodes. Set one resolution to 8000x1200, and the other to 4000x1200. now add a multi cam to both with two cameras connected. the multi cam connected to the 8k render to texture will do both the 4k resolutions, the other will do both the 2k resolutions. then take the output of the render to textures to 4 seperate image 2Ds, crop, rescale and arrange them in the viewport. that is the typical workflow I see for these use cases.
Also, region camera wouldn’t be necessary here, you could just use normal cameras too.
– Ryan