For ages I've run diskless terminals under Parallels, and aux/vga would quite cheerfully resize the Parallels window to match anything I told it.
Recently I had to migrate from Parallels to Fusion. Resizing doesn't work any more. Furthermore, I'm buggered if I can programmatically figure out what combinations of screen size+depth will work in Fusion without making the terminal instance panic. The list archives and the wiki are absent of advice.