@wasikm007 Your game should be using DirectX 11 mode by default. If you're adding the -dx11 command line argument and it's getting removed, perhaps that's because it's not necessary. What happens if you use the -dx9 argument instead: does it stick or does it disappear? My question is whether the issue is specific to DX11 or is about command line arguments in general.
As a side note, "chip" refers to the arrangement of transistors that makes up a processor of some kind. So a CPU (e.g. your Intel i5-9400F) is a chip. People refer to the integrated graphics chiplet within a processor as a chip too; yours doesn't have one. (That's what the F means.) Your GTX 1660 is a discrete graphics card. It consists of an actual chip that does the graphics processing, video memory chiplets, and various components related to power delivery, all welded to a printed circuit board (PCB), with a cooling apparatus attached. This is installed into a motherboard but is not welded to it or otherwise inseparable—it's a distinct piece of hardware you can add or remove at will.
Your dxdiag does use the word "chip" to refer to the 1660, but that doesn't mean it's a "chip" in the colloquial sense. The common distinction between "chip" and "card" is whether the GPU is its own distinct component, as yours is, or integrated into the processor.