Since the outlet runs house line voltage, ie 120v, anything you plug into it - if not using a transformer - would have to run at that same voltage. Running line voltage to exterior light fixtures can get cumbersome real quick (for ex, wire must be installed in conduit and/or dug down 36” deep..). Hence the value in going with a low-voltage system.
I have seen kits that come with a plug-in transformer on a 12v line, with photovoltaic on/off switching (here’s an example: https://www.target.com/p/john-timberlan ... A-80274937
). Something like this may be what you’re looking for.