Install VB Guest Additions before booting Ububtu-based OS

Question

I'm trying to install Elementary OS in VirtualBox, but the minimum resolution of the OS is 1024x768 and VirtualBox always boots in a much lower resolution. I can't install Guest Additions until the OS has been fully installed and I am on the desktop. I can't go through with the installation, though, because I only see about 60% of the screen in the top left corner. I've tried increasing video resolution to 128mb, but as I thought, that didn't work. Is there a way to increase the resolution with Guest Additions or something else before booting the system to install it?

Answer 1

I had an issue with the installation of Elementary OS 6 with VirtualBox for the same reason. The right side and bottom portion of the installer screens were cutoff. That area of the screen has buttons for back, submit, cancel.

I resolved this by making to selection to erase/complete install, then using the tab key twice followed by the enter key. Apparently this sequence of keystrokes allowed me to initiate the full installation script successfully.

Answer 2

same issue here,
end up add boot kernel parameter to fix this,
when first boot prompt(5 secs),
hit any key within the 5 secs count down to show boot options,
hit TAB to edit first option,
add the vga=ask to the end of boot kernel lines.

then it will show another 30 secs count down for VGA mode selection,
hit ENTER to choose proper one, in my case I choose 1280x800x32.

that's all,
more detail regarding boot vga parameters can refer to this URL.
https://linuxhint.com/set_screen_resolution_linux_kernel_boot/