You can do it two ways you can activate the created virtual environment on cmd and then type in notepad filename.py or if you want to use an advanced text editor such as sublime What you can do is you can download & install the sublime text editor on your system, suppose if you install sublime text editor copy the path of the folder of sublime text editor on to the environment variables on the system.
[you can see my sublime exe file name is subl from the image link below]
you can see the image by clicking this linkhttps://i.stack.imgur.com/NRFJE.png
so I just activate the virtual environment and type in subl filename.py in cmd so it opens the sublime text editor then type in your code and save it and after that you can run it by typing in filename.py. In this way you can create a file in virtual environment using notepad or other text editors.