Detailed documentation for configuring kernel virtual terminals is the realm of the operating system
For FreeBSD, for example, see the syscons(4), vt(4), kbdcontrol(1), and vidcontrol(1) manual pages.
There are rudimentary kernel-vt-kbdcontrol and kernel-vt-vidcontrol services that are parameterizable with service environment variables to apply settings using these utilities at boostrap.
However, it should be noted:
FreeBSD's framebuffer support is egregiously constrained, being only capable of 800×600 resolution at best.
FreeBSD's vt(4) reimplementation of its KVT subsystem broke vidcontrol(1). The design seems to be that one nowadays only sets the required display resolution at bootstrap time, via loader variables, and it is immutable via vidcontrol(1) at runtime.
GNU GRUB2 is hardwired in code to force the system into text mode when bootstrapping FreeBSD.
In the case of Linux-based operating systems, the nosh toolset does come with linux-vt and linux-console documentation to fill in some long-standing holes in existing documentation.
There are rudimentary kernel-vt-kbdrate, kernel-vt-loadkeys, kernel-vt-setterm, and kernel-vt-setfont services that are parameterizable with service environment variables to apply settings using various kbd, console-tools, or util-linux utilities at bootstrap.
(c.f the Linux How-To)