I would like to use iMac with thunder bolt port to view Hdmi output from a settop tv box (iptv)
I have not tried as of yet, but hoping I can just buy a hdmi to thunderbolt cable and put iMac in display mode to view tv box output? however on web search i keep seeing the use of and adapter box between output source and Mac, is this required?
you can't the hdmi is output only
there are some tvtuner boxes and others external boxes which connect by usb which claim that feature
that you can buy but the issue is that I don't see it being possible without compromising the hdcp drm https://en.wikipedia.org/wiki/High-bandwidth_Digital_Content_Protection
you can try checking
Can I connect a video camera to Mac using HDMI port?
more
No your iMac will not work as a monitor, because iMac's do not support cabled video input from third party devices.
Only certain iMac's can be used as a monitor for another Mac.
see > Use your iMac as a display with Target Display Mode - Apple Support
Plus only certain third party network devices can use VPN software like ScreenRecycler.
Use iMac to display Hdmi output from a device
