Default HTML editor in Visual Studio 2019 doesn’t include preview. You can select the Web Forms editor with a Design view, but it requires updates as you change code and doesn’t support full modern HTML capabilities.
The new HTML 11 extension for Visual Studio 2017/2019 provides a preview tool window automatically updated as you type and uses Chromium Embedded Framework v75 for HTML rendering:
https://tabsstudio.com/
Making Visual Studio perfect 