Microsoft's Link to Windows app for Android may soon support restarting or shutting down a computer or putting a PC to sleep. Code within the app was discovered that suggests the functionality is on the way, but nothing has been confirmed by Microsoft at this time.
Windows Latest found evidence suggesting that a pairing of Link to Windows and Phone Link will soon gain greater control of your PC. It's already possible to lock your PC from your Android phone, but the code suggests support for other actions is on the way.