I'll post my numbers and hopefully some of you will post yours and we can see what are good expectations: (On Windows 10 and Windows Server 2k19).
Core i7 8700B, 32GB Mac Mini. Games are run off an SSD drive via TB. Radeon VII via Razer Core X.
Doom 2016: 4K, Ultra, 100 fps
Doom Eternal: 4K, Ultra Nightmare, 60 fps (vsynced)
Division 2: 4K, High, 55 fps
Metro Exodus: 4K, High, 60 fps
Resident Evil 3: 4K, Ultra, 60 fps
State of Decay 2: 4K, High, 45 fps
Gears of War 5: 1440p, High, 40 fps
Forza Horizon 4: 4K, Ultra, 60 fps
Hunt: 4K, High, 45 fps
Apex Legends: 1440p, High, 60 fps
I'd be willing to add more entries. I'd also be willing to compile results in an xls so we could see what kind of settings, engines and the like operate best on egpus.
-2018 Mac Mini Core i7 8700B, Radeon VII via Razer Core X