Here is a smart plug with Alexa and HomeKit support that can be used for your landscape lights. The Lutron Caseta Outdoor Smart Plug has a polycarbonate body and IP65 rating. It comes with a Pico remote that lets you turn your lights on/off at the touch of a button.
This smart outdoor plug works in -4 to 122F temperatures. It can handle up to 1000ft sting lights.