I think once installed windows 10 it is possible to have some gains in games like "witcher 3".... even with "old" graphic chips
DirectX was created in the late 90's by Microsoft specifically for games to have more direct access to hardware. Back then the big thing was 3DFX VoodDoo and Glide (if any of you remember). DirectX for graphics wasn't really a big thing until 3DFX died and DirectX 9 came out. Anyone remember the ATI 9700 Pro? It was awesome for several years, right up until NVIDIA release the 6600 and 6800 cards (some were bundled with Doom3). Anyway, enough walking down memory lane...You can't. Directx is a Microsoft Windows program. You will need to install Windows 10 on your mac before you can get DX12.