I have a Mac Mini (2014) with MacOS Mojave on it.
It is constantly plugged into an electrical outlet though almost constantly completely turned off (neither hibernate nor sleep). Moreover, it usually has immediate access to the internet when turned on (i.e. constant Wifi hotspot available that it knows the password for and connects to automatically).
My question is this: how do I schedule it to automatically turn on at a specific time of the week (specific day and hour) without me being there to press the power button and then have it do updates automatically if there are any and then, finally, shut back down. Again, this would ideally be done without me being there to log in or press any button. Since it has all the resources available (power and an internet connection), I imagine this should technically be possible to automate.
You could use a combination of two System Control Panel structures.
There’s no way to make it boot, check, shut down in a single move, but you can do it in 2 steps…
Firstly, you can set it to auto-boot [it can do this from “completely off” so long as it’s got mains power] on a schedule & shut down any time later. Energy Saver prefs > Schedule… I just threw some fairly random parameters in this for the picture, as I don’t use it this way myself…
Combined with that, so it will check & action any updates it finds during that boot period, use Software Update > Advanced & check all the boxes – this panel is new since Mojave, but essentially the same options are available in earlier OSes, in the App Store Control Panel. You can’t dictate the interval between checks for this, but if it hasn’t seen the internet for a day or two, it will just do it automatically, shortly after boot.
I’m not absolutely certain all updates can be actioned this way with absolutely no admin intervention, but it ought to get you very close to that.