An attribute set of option values passed to rclone mount. To set a boolean option, assign it true or false. See https://nixos.org/manual/nixpkgs/stable/#function-library-lib.cli.toGNUCommandLineShell for more details on the format.
Some caching options are set by default, namely vfs-cache-mode = "full" and cache-dir. These can be overridden if desired.