Earlier quoted context omitted.
Cloudflare plugin, that does what exactly? You mean like this one? https://github.com/caddy-dns/cloudflare (I'm using it today, works great. Assuming that's what you meant.)
How to use this plugin with a Caddyfile?
tls {
dns cloudflare
}
Replace with your API token, or you can store it in an env variable and use {env.CLOUDFLARE_API_TOKEN} for example.