I know that I can just turn my iPhone 6s, but I'd like the actual orientation to change. I'll like to be able to share my screen with someone via Skype and see it in the landscape orientation.
I've moved your post from the Photoshop forum to the Sketch forum where you are more likely to get a response to your question
Sorry. On phones, the mobile apps only support portrait mode. So even if the device itself is positioned in landscape mode documents are always in portrait orientation.
It was a decision that was made early on with the apps and I don't believe there is a plan to change that, but I'll share your comments with the drawing teams.