Thanks so much everyone for all of your help.
So if I understand correctly, using the free version of Resolve 17 I should be able to import the 4096x2160 16bit dpx files. The timeline will be limited to UHD 3840x2160, so any work I do (and any exports) will be at this resolution. The 16bit color should not create any issues.
One final question - are there any settings that I need to check in order to be sure that the color remains 16 bit? I know I will need to select DPX 16 bit when I choose my export render settings, but is there anything else I need to do? I see bit depth settings under Project Settings> video monitoring, but I assume this has no effect on the actual footage.
@Marc Wielage - Yes, you're absolutely right, if I were regularly doing work that required .dpx files I would definitely be using Studio. All my current work is on a micro-budget documentary in 1080P. The .dpx files will be from an unrelated film scan from which I will need to export a few selects for another company. That said, I really want to support Resolve and will probably upgrade to Studio in the near future - if only to play around with the Speed Editor