To install pip packages offline first download all the packages, for example to install pgcli:

pip download pgcli -d packages_downloads

Then you can tar and share the file to your offline server:

tar -cf pgcli.tar.gz package_downloads/

In the server without internet you can unarchive to dir named wrk:

tar -xvf pgcli.tar.gz wrk

Then to install do:

pip install --no-index --find-links "./wrk/" ./wrk/pgcli-4.1.0-py3-none-any.whl