If your PC is connected to any network, wireless or wired, another PC can connect to it. More common protocols like RDP are just what the public understands. RPC, DCOM, and WMI are examples of other Microsoft protocols that allow access to your computer remotely, but they’re more secure than RDP in some ways.
Yep, mine woke up on it’s own a couple times even though RDP was off. I happened to hear the fan come on and the display light up and I jumped out of bed to hold down the power button before it could fully boot. Someone had power it up remotely. Haven’t trusted MS since.