The default setting of Windows 10 Update is "Automatic" that will install new updates automatically when the updates are pushed out by Microsoft. In this mode, Windows will wait until your computer is idle and it will start downloading and installing new updates. While you can't control the downloads and installs, you can however control the restarts.
Go to Windows Updates (WIN+S, Windows Update).
Go to Advanced Options.
Select "Notify to schedule restart".
Now, Windows will ask you for a time to restart your machine.