Barring rotating the monitor - which is lossless
That triggers a memory. One of those ideas I had but was in no position to implement. Back in the day when large CRT monitors were very expensive, and some people used full page sized monitors to do desktop publishing or whatever, I thought, since a normal monitor is wider than it is tall, instead of having a humongous monitor, why not just have hw that rotated the output 90 degrees and have a stand with a hinge to tilt the monitor, the "width" becoming the "height." Years later I saw one with that stand and hinge so I assume they also did the rotation in hardware.
Funny I totally forgot about that.