As long as the extension is active and you have a Python file loaded in VS Code, it should run automatically. You can also configure two major options for Pylance right in the VS Code interface.

With the official Python extension provided by Microsoft ... You can customize almost every aspect of VS Code’s interface to suit your preferences, from themes and icon sets to keyboard ...

Syntax highlighting in Python code -- along with other language-specific "smartness ... Other highlights of the update include: Revamped testing interface: By leveraging the built-in test explorer in ...