You're not quite right but, not really wrong either. Microsoft will support Windows 10 Version 1903 until 2023. However there will be a new version of Windows 10, coming along shortly.
Initially, they said that they would produce 2 new Versions of Windows 10, each year. I gather that the plan has changed slightly, and it will be 1 version each year.
According to Microsoft, Windows 10 is the ultimate version and will be revamped on an annual basis.
Most of us are somewhat sceptical about that but, you should be safe for the next 3, or so, years