I have been using an old PC as NAS and running docker containers (Immich, Nextcloud, paperless-ngx etc.). I got 5 3.5" HDD disks and a Nvme. Even on idle, I am consuming 50-60w. A friend of mine is selling a Qnap NAS which is a dedicated machine and probably consumes less power, although I don’t know if it’s worth it.
that’s not always the default setup, especially with enterprise drives. also if you have some kind of monitoring, that can keep the drives from going down (for that, use linux hd-idle instead of drive internal idle timer), and it can also wake them up (for that, prometheus node exporter’s smart collector first checks whether a drive is up, and only then collect stats). Interestingly, checking temps with smartctl always spins up my drives, while linux hwmon can give me live temp stats even while the drives are down