iPhone will not lock into landscape mode.

So for some reason Apple removed the workaround to use the assistive touch rotate screen options whilst being in portrait mode lock.

The issue has been a topic since October 2015 and they still won’t add landscape lock. But now they’ve even removed the workaround.

And yes I know 180 degree turn can “hold” landscape in “some” apps. This doesn’t fix the problem that when I need to distract my child in the car on long trips he can no longer watch abc kids or anything without it flipping back to the tiny portrait mode.