Probably you are making an application that is based on .NET 5 or 6 (Core). The WebBrowser control is available in case of .NET Framework. Try creating a new “Windows Forms App (.NET Framework)” project.
However, there is a new improved control — WebView2 — which supports the modern Web sites. See: https://learn.microsoft.com/en-us/microsoft-edge/webview2/get-started/winforms. You can also use it in WPF application.