I’ve been using No-IP free plan for years without issues. Inputted the credentials to my routers DDNS client and then basically forgot about it. Free users need to confirm their account once a month via email but that’s just one click.
If your domain registrar happens to have an API to update DNS entries, you could implement DDNS yourself by writing a simple automated script to check the external IP (e.g. via ipify.org) and if it’s changed from the last check then call the API to update the DNS entries.