I just built my new PC box, here is a list of some components which I think that might be related to this question:
But somehow, I cannot do the Miracast to connect to my Smart TV.
I just built my new PC box, but I cannot connect wirelessly to my Smart TV, through Miracast.
Miracast is supported entirely by the GPU and the Wi-Fi adapter. This means that the display driver for the GPU and the driver for the wireless adapter both must support Miracast. The wireless adapter must also support Wifi Direct.
Miracast is a graphic card standard. Miracast requires a display adapter which supports Windows Display Driver Model (WDDM) 1.3 which to the best of my knowledge includes all current AMD and NVIDIA GPUs, it also requires and a Wi-Fi adapter that supports Wi-Fi Direct.
I've noticed while NVIDIA claims support for WDDM 1.3 and Miracast, it turns out Nvidia actually cut support for Miracast back in 2016; meaning you'd need some of their older drivers and a card available in 2016 to make it work.
I can confirm (based on the fact I have the same exact card), that the current Nvidia drivers for the Nvidia 2080 Ti, do not support Miracast. This means that since you do not have a GPU that supports Miracast, you will be unable to use Miracast, with the hardware you have.
Card name: NVIDIA GeForce RTX 2080 Ti Manufacturer: NVIDIA Chip type: GeForce RTX 2080 Ti Miracast: Not Supported by Graphics driver
It appears that Nvidia dropped support for Miracast awhile ago.