I bought the anthology
can I get them in windowed mode

It may be possible to get DD and BD to run in a window, using third party programs.

Is it possible to switch this game to window mode?

Windows Borderless Gaming app


With D2:DC, there is a configuration file edit to run it in a window. Edit the file below in a text editor and change the one to a zero in Fullscreen="1".
C:\Users\<UserName>\AppData\Local\Divinity 2\Profile\graphicoptions.xml

You may need to set Windows Explorer to show hidden files and folders (covers Vista through Win 10).