Yes, you're right, and I have both python and python3 packages installed.
Let's say I want to install Electrum, after having downloaded it.
sudo python3 -m pip install --user Electrum-3.3.6.tar.gz[fast]
then I get back (among other things):
Processing ./Electrum-3.3.0.tar.gz
Complete output from command python setup.py egg_info:
Error: Electrum requires Python version >= 3.6.1...
