Use an iMac 5k or iMac 4k 2017 as a target display with Macbook Pro retina early 2013 I have a Macbook Pro Retina early 2013 and I'd like to know if it's possible to use a brand new iMac 5K maybe the 4K 2017 as a target display for that macbook, is that possible, do I need an adapter from Thunderbolt 2 to Thunderbolt 3? 

Regards.
According to this article on AppleInsider the 2017 4K and 5k iMacs do not support target display mode.