How do I make the Pure-FTPd service use a config file on Debian 10?

Hello,

I am on Debian 10 and I have Pure-FTPd installed.

The service was configured to run the daemon with command line arguments as the config, but I want to use a configuration file with it.

How can I make the service use the configuration file instead?

edit: if it helps anything, it's in init.d and systemd is used to run it.

Thanks in advance.