Thanks to everyone who added their input to this question. It helped me find the solution and I can confirm like others here that the following setup works.
- Mini DisplayPort to Dual-Link DVI Adapter cable (A1306)
- OWC 14-Port Thunderbolt 3 Dock (it's the only dock that I know of that has the mini DisplayPort)
- Apple Cinema Display (A1083) - (mine is a 2004/2005-ish 30 inch)
- ASUS ProArt 27 inch monitor
- Mac Mini M1 2020 running Big Sur latest updates
Connect OWC hub to your Mac. Connect ACD to the Mini DisplayPort cable and then plug it into the hub's mini Display port. To set the resolution to 2560x1600 you hold down the 'option key' when choosing Scaled in the Display preferences.
I connected my ASUS ProArt to the HDMI port on the mac mini with a resolution of 2560x1440.
I did this and it has just been working without needing to reset the resolution on restarts. My 2020 M1 Mac mini is just
the $699.00 standard version with no upgrade running the latest Big Sur 11.2.
The Mini DisplayPort to Dual-Link DVI Adapter cable can be bought on ebay or some stores that still have it in stock.
Hopefully this helps anyone who is still wondering which parts to buy. Thanks to everyone on here with all the input that
has been very helpful. cheers