I want to build some basic desktop applications? which workflow is largely used? why? how to start to build a desktop application?
Electron.js is an option but not sure its right option for desktop application?
Maybe just try watching a YouTube video on Python
Tkinter or another Python GUI package.
You could also use Java or .net, both have much more developed and mature offerings for Desktop apps over Python. There's a steeper learning curve with Java/.net than Python to get good, though to do serious commercial grade Desktop apps the Python packages don't offer near as many features as say C# or C++. Even Java has limitations in Windows but quite rich for all platforms with their JVM. .Net has core and Winforms and WPF has been recently open sourced in an effort to get them to run on non-windows systems.