You can get FreeBSD (and maybe others) installed without graphics acceleration and that will still allow you go install and run KDE Plasma. However, the experience will be somewhat poor. What made me take note is that when I looked at KDE Plasma settings under Display and Monitor the refresh rate of the monitor was 0hz. When I was at a remote location I decided to run using x11 forwarding the settings program where I found the refresh rate properly set for that monitor, which was 60hz.
In order to actually install the accelerated graphics you must install the appropriate drm-* driver. This is done with the following command.
sudo pkg install graphics/drm-kmod
This will download and install nearly 100 items pertaining to various graphics technologies, such as AMD, NVIDIA, and Intel.
In my case I just wanted to install the accelerated driver for the Intel HD Graphics 530.
Once this is done you would then issue the command to enable the driver. It is enabled in your /etc/rc.conf file as a single line. There’s a program that you can execute at the command line that will do the job for you or you can manually edit the file yourself.
The command is as follows:
sudo sysrc -f /etc/rc.conf kld_list+=i915kms
If you then cat /etc/rc.conf you will see the line “kld_list=”i915kms”.
After this just reboot your computer.
Note that your text spam from the boot will look smaller and crisper. It should then automatically switch to graphics mode and load the SDDM greeter for you to log in.