doc: Explain how to query values for --platform and --python-version

docs/html/cli/pip_download.rst

@@ -47,7 +47,12 @@ constrained download requirement. If some of your dependencies are not
 available as binaries, you can build them manually for your target platform
 and let pip download know where to find them using ``--find-links``.
 
+.. note::
 
+   To determine the appropriate values for ``--python-version`` and ``--platform``, you can query the target system using the following commands:
+
+   - For the Python version, use :func:`sysconfig.get_python_version() <sysconfig.get_python_version>`.
+   - For the platform, use :func:`packaging.tags.platform_tags() <packaging.tags.platform_tags>`.
 
 Options
 =======

docs/html/conf.py

@@ -78,6 +78,7 @@
 intersphinx_mapping = {
     "python": ("https://docs.python.org/3", None),
     "pypug": ("https://packaging.python.org", None),
+    "packaging": ("https://packaging.pypa.io/en/stable/", None),
 }
 
 # -- Options for towncrier_draft extension --------------------------------------------