Apple does not support the Target Display Mode for the iMac (Retina 5K, 27-inch, Late 2014) and later iMac models.
It would be great, if you could offer it with the Pluggable USB 3.0 Windows SuperSpeed Transfer Cable and the Bravura Easy Computer Sync software for Mac
I would like to use my iMac as a remote display (including audio, keyboard and mouse) for my notebook in my home office.
If you are looking to some forums, there a lot iMac owner searching for a solution, to close this unsuspected gap of the iMac
looking forward to hear something from your support.