Using vncviewer it shouldn't be any more difficult to change the resolution of the remote desktop than simply changing the geometry e.g.
vncviewer 192.168.4.126:2 -geometry 1024x720.
However, that only changes the dimension of the viewing window, not the desktop size itself. To change the desktop resolution we have to change it at the VNC server. To do this I installed vnc4server as shown below:
sudo apt-get install vnc4server
Then I started vnc4server with the geometry size I wanted the desktop to be e.g.
vnc4server -geometry 1024x720
Then I connected to the VNC session using the vncviewer, and the desktop was at the size I expected.
Note: When running vnv4server on the Raspberry PI using Raspbian, it defaults to Openbox (which was ideal for me).