As you know we can output a string to the kernel /init/main.c
using printk.
I want to know if there are other function to make the appearance look better. is there any drawing function? color settings? if there is, i would thank if you name a few.
Well, you're printing to a terminal, so you could try standard ANSI color escape sequences.
A raw Linux terminal doesn't support all of them but definitely has color. I'm not sure whether it'll work at the kernel level or not but worth a try.