Default [Q] Question about a locked bootloader

I have searched and searched and am only asking here because this is my current device and I am not sure if this is a device specific question. With a locked bootloader, does it check the system folder for things like superuser and other apps that have to be written to the system directory, or am I safe to install those things without bricking my device?

I have a weird understanding of how android works I understand more than the average user and am comfortable with rooting but I am also extremely paranoid and not knowing this sort of thing makes me uncomfortable. Help is appreciated