Windows Phone does not make many adjustments for large-screened handsets, but Windows 10 Mobile goes slightly further, offering two features reserved for phablets like the Lumia 1520.
The first is a new, more dense task switcher with 4 apps within easy reach simultaneously.
The next is the floating keyboard, which can be positioned all over the screen for easier one handed text entry.
We expect improved stylus support to arrive eventually, but this is not evident yet so far in the Technical Preview and will likely require phones with special hardware.
See the improvements in the video by GeeksonGadgets above.