First install your desired verison of python from python.org
During the installation wizard check the add to path option at the bottom of the wizard so that you dont manually have to add python to path from environment variables
Go to the directory where you want to create the python environment
Run the command py -0 to check which python versions you have available
Then run the command "py -//python version// -m venv //environment name// "---> "py -3.9 -m venv env3.9" to create a virtual environment which uses your desired python version