OK, I just noticed that the new FFT API will most likely be released in v1.7.0. It is currently available in the nightly releases of PyTorch. Note that the nightly builds are not stable, so you probably should not use them for anything important. If you want to install the nightly build and get access to the new (and simplified) FFT API, use https://pytorch.org/get-started/locally/ 2 and select “Preview (Nightly)”.
If you are running a Linux distro with a GPU, you can install the latest nightly build with
pip install --pre torch torchvision -f https://download.pytorch.org/whl/nightly/cu102/torch_nightly.html

or if you do not want GPU support use
pip install --pre torch torchvision -f https://download.pytorch.org/whl/nightly/cpu/torch_nightly.html

For any other OS or specific CUDA versions, use the configuration tool on https://pytorch.org/get-started/locally/ 2.