You can reload your Caddyfile with no downtime (need to confirm that), and without restarting Caddy by running caddy reload.

I only ever run Caddy from a Docker container, in which case I just run the below.

docker exec --workdir /etc/caddy --interactive --tty <caddy-container-name> caddy reload

I always just used to stop and start Caddy… Quick though that is, it pays to read the docs!