You can change the behavior of a DOS APP if you change the setting in VMware Workstation general preferences. By default Full Screen is set to autofit. However, there's no vmware tools for DOS 6.22 so the max resolution seems 700x400 and in full screen the native windows/linux resolution of the host will be used and centered you see the DOS window with the 700x400 resolution. If you change to Stretch guest you should have the wanted full screen.
Do have other resolutions you need to work with ANSI or a Vesa aware application. There was an UniVesa driver for DOS available long time ago but it was only needed for applications which could display at other resolutions.
