Do Blue, Yellow, And Red Make Black?

Or just Brown?

“Black” is merely a concept.

When all spectrum of light that you can perceive is absorbed (instead of reflected), that is what you will consider “black”.

All creatures with eyes and/eye spots see different spectrums of what is whole light (whole or white light within their context).

It depends on whether you're talking paint pigments or light hues. The paint would probably get you something brownish. The light would get you white.

Also, Blue, Yellow, and Red are only used as a guideline for color aesthetics. They can not make all colors. To make all colors you need the physical primary colors of cyan, magenta, and yellow.

One creature can perceive an object as being black, but another creature might perceive it as indigo.