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.
Most of the power draw is from the hdds. I have the same issue. If you want less power consumption. Invest in SSD or SSD and HDD hybrid where you store quick access files on SSD and rare access on hdd (then you can spin them down with timeout of , let’s say 30-60 min). This should save some energy