Is it possible to add directories to docker container?

I’m still somewhat new to Docker and the repo, but I’m interested in understanding how to add additional directories to be used as mount points for external volumes created in Docker. Example, the plex container does not have a music directory and I’d like to create one so that I can mount a volume to it. This is just one scenario of a few I’ve ran into. My work around thus far, depending on the technology, is to use the /mnt directory which is there by default. Can anyone point me in the right direction?

take a look at
Volumes -