The wheel file is only 184.2 MB, but unpacked (i.e. the folder in site-packages) is 936 MB. But this is perhaps to be expeced?
(venv) λ pip install torch==1.7.1+cpu -f https://download.pytorch.org/whl/torch_stable.html
Looking in links: https://download.pytorch.org/whl/torch_stable.html
Collecting torch==1.7.1+cpu
  Using cached https://download.pytorch.org/whl/cpu/torch-1.7.1%2Bcpu-cp39-cp39-win_amd64.whl (184.2 MB)
Collecting numpy
  Using cached numpy-1.20.1-cp39-cp39-win_amd64.whl (13.7 MB)
Collecting typing-extensions
  Using cached typing_extensions-3.7.4.3-py3-none-any.whl (22 kB)
Installing collected packages: numpy, typing-extensions, torch
Successfully installed numpy-1.20.1 torch-1.7.1+cpu typing-extensions-3.7.4.3