Have a look here: [https://github.com/paperless-ngx/paperless-ngx/blob/main/docker/compose/docker-compose.postgres.yml](paperless-ngx docker-compose.yml)
down under webserver: you change data:/usr/src/paperless/data to /path/to/where/you/wantorhave/your/files:/usr/src/paperless/data. Same for the media path and you're done. paperless now uses a folder on your machine instead of a volume.
If you want to be clean you will then also remove the volume declaration at the bottom of the file.