On the bottom right of the PyCharm screen you will be able to setup the interpreter options for your project like creating a new one (with venv, conda, poetry etc) or switch between multiple interpreters (if you need to test you app with multiple versions of python for example).

Easier one to use in my opinion is venv, it will create a .venv folder in the project and store the installed modules there.

More information here in the official docs: https://www.jetbrains.com/help/pycharm/configuring-python-interpreter.html#interpreter