This was already discussed further on our Discord server. Solution; set sensor resolution to 4k and preview size to to desired size, eg:
camRgb.setResolution(dai.ColorCameraProperties.SensorResolution.THE_4_K)
rgbCam.setPreviewSize(2048,1024)And for reference, franva tried to run semantic-segmentation-adas-0001 that has input size 2048x1024.