The Intel Iris Xe graphics hardware is essentially the predecessor GPU developed prior to the Intel ARC Alchemist discrete video card architecture.
The tested benchmark performance levels has the GPU perform above that of a GT 1030 but substantially less than that of a GTX 950. It performs well below 20% that of a RX 550 GPU from AMD. The GPU is essentially competing against the Nvidia MX350 GPU.
So the problem is not that it is not supports DX12, the problem is that it does not reach the minimum GPU requirement, which is a 1060 6GB ( or equivalent GPU )