NVIDIA GeForce RTX 3090 with CUDA capability sm_86 is not compatible with the current PyTorch installation

Your install steps focus heavily on installing the CUDA toolkit, which will only be used if you build PyTorch from source or a custom CUDA extension. The pip wheels and conda binaries ship with their own CUDA runtime that you are selecting during the install process.
You would only need to install a proper NVIDIA driver and should be able to use the binaries (unless you want to compile CUDA code and build PyTorch with it or an extension).