sQlite3 output to tkinter treeview - how do I set / increase width of the output?

[Larz60+]

I have example of that in one o f my projects here: https://github.com/Larz60p/CaliforniaPublicSalaries
see src/CaCompGui.py for entire code

        self.download_tree = ttk.Treeview(frame3b,
                                          height=self.treeheight_download,
                                          padding=(2, 2, 2, 2),
                                          selectmode="extended")
        self.download_tree.heading('#0', text='Files to download',
                                   anchor=tk.CENTER)
        self.download_tree.column('#0', stretch=tk.YES, width=400)

        tree_down_scrolly = tk.Scrollbar(frame3b, orient=tk.VERTICAL,
                                         command=self.download_tree.yview)

        tree_down_scrolly.grid(row=0, rowspan=self.treeheight_download,
                               column=4, sticky='ns')

        tree_down_scrollx = tk.Scrollbar(frame3b, orient=tk.HORIZONTAL,
                                         command=self.download_tree.xview)
        tree_down_scrollx.grid(row=self.treeheight_download + 1, column=0,
                               columnspan=4, sticky='ew')
        self.download_tree.configure(yscroll=tree_down_scrolly)
        self.download_tree.configure(xscroll=tree_down_scrollx)
        self.download_tree.grid(row=0, rowspan=self.treeheight_download,
column=1, columnspan=3, sticky='nsew')