I actually asked this question some months back, and got some engaged responses: DT3 large database performance versus new hardware choices.
I’ve ended up with the new Mac Mini with 16GB of RAM which flies along. I also got a refurbished MBP 2015 with 16GB, and this has unexpectedly become my main machine since the lockdown and working from home. I’ve never found this golden oldie limiting for my work and DT uses comparatively moderate system resources.
(I’m also recording and encoding video for my teaching, and here it’s another matter: the MBP fans sound like the whole machine is taking flight, with the processor pushed to the max – all just to compress a quick mov. to MP4).
Your mileage may vary (and more is always bettter if you can afford it) – but I’d say 16GB of RAM is more than sufficient. If you are planning on editing video files rather than storing them, perhaps err on the safe side. Others will be better equipped than I am to advise on using video in DT, as my DBs are all text and static images.