Low usage power saving recommendations request?

I'm new to selfhosting and I find myself rarely using the server, only when I need to retrieve a document or something.

I was thinking of implementing something to make it power on, on demand, but I'm not sure if this might be harmful for the HDDs, and I'm not sure how to implment it if so.

What's your recommendation to do so? I'm running a dell optiplex 3050