Is it possible to use child window created in Win32 API as a container for another windows (controls - buttons, edit fields etc.)?

Or is there any other way how to use container in Win32 API? The goal is to create a simple user interface for application?

Why not? You see child windows with buttons etc. all the time, just look at your browser to see them in action. If you use FF or IE7/8 each of those tabs are just child windows.

You might want to investigate either CLR/C++ (Midrosoft Forms) or C# which will make you a lot more productive than using win32 api functions directly.