Welcome to the forum @ace263
Duplicati components would be worth a read if you’re not familiar. Which service are you asking about?
The GUI installer installs the TrayIcon which includes the Server component and starts at the user login.
Duplicati.WindowsService.exe is how one adds a Windows service. One can add tray icon to go with it.
Most people who want something run at boot would probably run through a Windows service, I imagine.
Typically they are probably run as SYSTEM, but both Duplicati and Windows’ own tools provide options.
I’m also a little unclear how the patches and updates situation impacts what you’re trying to accomplish.
EDIT:
Different ways to make a Duplicati backup also covers options, including command line, which I omitted.
There are a lot of ways to do things, and I’m not quite sure what you’re looking for. Maybe you can clarify.