Currently there is no possible way to set Table Preferred Width despite having this setting available within Word settings menu: Table -> Table Properties. Requesting addition of a feature to assist with this, since manually setting table width via xml modification (w:TblW modification to fixed width, etc), column width, or cell width, do not actually check this box within Word (although I have gotten to the point of having a greyed out default width that gets enabled when I go into that settings menu and check the box manually for each table).

Current settings only allow for 'soft' fixed width setting, but everything defaults to auto-width and column/cell resizing, even fixed width, once you resize your window to be smaller than the table width. This isn't a 'true' fixed width and Word does have this option available via the table settings menu if you manually check a box.

Requesting that python-docx gets a way to 'check this box' within word settings via some command for the table during initialization of the table in the python script, so that you don't have to manually select each table and enter a menu window to check this box for every table in the final document.