opening or unzipping Xcode 8.3.2.xip.file
So you asked two questions, and I'll address the second one first, "Would you have to do it from the command line?", no, it does not have to be done from the command line.

As to your first question, "How can I "unzip" or extract files from Xcode.8.3.2.xip.file on 2009 MacBook?", you would have to have the Late 2009 MacBook, which supports macOS Sierra, and have macOS Sierra installed. Then assuming the Xcode.8.3.2.xip.file was in your Downloads folder, you simply double-click it.

This will cause Archive Utility to expand the file by first verifying the digital signature it contains, and expand it to the Xcode.app application bundle, at first located within the TMPDIR, e.g on my system it was /private/var/folders/7c/wmqb3p_14hq_6g1vtj20rv0h0000gn/T/Cleanup At Startup/.BAH.vW5Gr/Xcode.app and then it gets moved to the, e.g., ~/Downloads folder, where you'd then manually move it to /Applications.