How can I download an output of a Python file inside a container to my host machine's dedicated folder?

This is a somewhat difficult question, which can be solved in a variety of ways. The first, which I think you understand already, is that we do not usually want to store out output in a container, because it is likely to go away and be lost when the container is shut down. The usual solution is to have the program actually store the data somewhere else, or move it somewhere else after creating it. A very simple example might be to have your program, when it is done creating an output file, then have it use ftp to an ftp server somewhere. (in python you can use ftplib). Or you might send the output to a web server that permits uploading files. Or connect to a database server and send the data as you retrieve it. All of these will require some work, and creating some place to send the data.