Really disappointing specs tbh.
They have had roughly 6 years of dx12 "beta" in Warhammer. There's no excuse for it to not have been updated. Adding all this extra content to an already heavily CPU bound game is just not going to work well.
The newer features of VRS and Mesh Shading could significantly improve performance. Upscaling tech could be useful as well, though thousands of units on screen moving at random paces, directions, clumped,.etc it may be difficult to make it work correctly.