Almost! `python3-virtualenv` is virtualenv, the third-party tool that ultimately inspired `venv`. `python3-venv` is the Ubuntu/Debian breakout package for `python -m venv`.

TL;DR: Install python3-venv, not python3-virtualenv.

(Ubuntu and Debian's decision to break out core parts of the Python standard library has been an unending source of problems. PEP 668[1] is an in-progress effort to better categorize these kinds of distro changes and improve the user experience around them.)

Edit: I should also qualify: virtualenv is still maintained and useful; venv is contains the subset of virtualenv's functionality that 99% of users use.

[1]: https://peps.python.org/pep-0668/