The webbrowser module can open URLs in a web browser from a script:
webbrowser.open("https://www.python.org")
It selects the default browser and can open URLs in a new window or a new tab:
webbrowser.open_new("https://www.python.org")
webbrowser.open_new_tab("https://www.python.org")
The webbrowser module can also be used from the command line
python -m webbrowser "https://www.python.org"
python -m webbrowser --new-window "https://www.python.org"
python -m webbrowser --new-tab "https://www.python.org"