What you can do for now though is use the adapt command to convert your Caddyfile to JSON and then update the connection policy to enable client auth: Home · caddyserver/caddy Wiki · GitHub
I’m a bit swamped at the moment with things, but I want to make this configurable with the Caddyfile, so if you want to contribute it, feel free to open an issue to discuss it first, and then a PR would be greatly appreciated!