~/Library/Caches/pip   master ●  $ pwd
/Users/organic/Library/Caches/pip

 ~/Library/Caches/pip   master ●  $ cat pip.conf
[global]
trusted-host = pypi.python.org
               pypi.org
               files.pythonhosted.org

~/Library/Caches/pip   master ● $ python3 -m pip install --trusted-host pypi.org --trusted-host pypi.python.org --trusted-host files.pythonhosted.org --upgrade pip requests matplotlib
Requirement already satisfied: pip in /usr/local/lib/python3.9/site-packages (20.3.3)
Requirement already satisfied: requests in /usr/local/lib/python3.9/site-packages (2.22.0)
Collecting matplotlib
  WARNING: Retrying (Retry(total=4, connect=None, read=None, redirect=None, status=None)) after connection broken by 'ProtocolError('Connection aborted.', ConnectionResetError(54, 'Connection reset by peer'))': /packages/10/e7/1a9fd930260671a06f73aa882769e5e0d10e5924dd96161f138e26a2f095/matplotlib-3.3.3-cp39-cp39-macosx_10_9_x86_64.whl
  WARNING: Retrying (Retry(total=3, connect=None, read=None, redirect=None, status=None)) after connection broken by 'ProtocolError('Connection aborted.', ConnectionResetError(54, 'Connection reset by peer'))': /packages/10/e7/1a9fd930260671a06f73aa882769e5e0d10e5924dd96161f138e26a2f095/matplotlib-3.3.3-cp39-cp39-macosx_10_9_x86_64.whl
  WARNING: Retrying (Retry(total=2, connect=None, read=None, redirect=None, status=None)) after connection broken by 'ProtocolError('Connection aborted.', ConnectionResetError(54, 'Connection reset by peer'))': /packages/10/e7/1a9fd930260671a06f73aa882769e5e0d10e5924dd96161f138e26a2f095/matplotlib-3.3.3-cp39-cp39-macosx_10_9_x86_64.whl
  WARNING: Retrying (Retry(total=1, connect=None, read=None, redirect=None, status=None)) after connection broken by 'ProtocolError('Connection aborted.', ConnectionResetError(54, 'Connection reset by peer'))': /packages/10/e7/1a9fd930260671a06f73aa882769e5e0d10e5924dd96161f138e26a2f095/matplotlib-3.3.3-cp39-cp39-macosx_10_9_x86_64.whl
  WARNING: Retrying (Retry(total=0, connect=None, read=None, redirect=None, status=None)) after connection broken by 'ProtocolError('Connection aborted.', ConnectionResetError(54, 'Connection reset by peer'))': /packages/10/e7/1a9fd930260671a06f73aa882769e5e0d10e5924dd96161f138e26a2f095/matplotlib-3.3.3-cp39-cp39-macosx_10_9_x86_64.whl
ERROR: Could not install packages due to an EnvironmentError: HTTPSConnectionPool(host='files.pythonhosted.org', port=443): Max retries exceeded with url: /packages/10/e7/1a9fd930260671a06f73aa882769e5e0d10e5924dd96161f138e26a2f095/matplotlib-3.3.3-cp39-cp39-macosx_10_9_x86_64.whl (Caused by ProtocolError('Connection aborted.', ConnectionResetError(54, 'Connection reset by peer')))