Version: 2020.3
public bool autoResize ;

説明

Option to allow the column to resize automatically when resizing the entire MultiColumnHeader.

The default value is true which means that the column will resize automatically if the rect of the MultiColumHeader is changed. If false then the column width will remain unchanged until the user changes it by dragging. It is a good idea to have at least one column that are auto resizable to adjust to the width of the MultiColumnHeader.