The ability to resize columns exists in workspaces throughout a tenant. This same ability should apply to the information on the dashboard.
The Item Descriptor field in the My Outstanding Work section of the dashboard in particular is rather short and can truncate valuable information that would otherwise allow a user to find an item they need to address more quickly than previewing or opening all similar items. For some items and workspaces a shorter field length may be fine; for others the ability of the user to resize these columns and save any display changes would enhance productivity.