How to change terminal screen size/resolution on Ubuntu 19.04 Server with VirtualBox? [duplicate]

I installed Ubuntu Server 19.04 from VirtualBox on Windows Host. I have a terminal screen 800x600. VirtualBox does not provide me an option to change resolution.

How do I change the terminal resolution?

Tried:

1) Downloaded VirtualBox Guest Additions from virtualbox.org, mounted media, and installed.

2) sudo apt-get install virtualbox-guest-additions-iso

Wonder if the problem is because it's the Server version, and there's no graphic interface or X11.

Guest Additions installed:

$lsmod | grep vboxguest

vboxguest 331776 1

Looks like GRUB might have something to do with it.

Looks like I need a graphical terminal.