I guess part of the confusion for me is that when I learn these, the “complementary” colors were pairs - it was the color on the exact opposite side of the color wheel. Here there are three., or triadic colors. This site offers different triadic colors.
But again, color is a complicated science wrapped in a great deal of human subjective interpretation. And the idea of what a color wheel is has changed over time - see this page and the two color wheels they show. And all of this depends on whether we are talking about additive or subtractive colors. This is a complex field. And from culture to culture there is a lot of subjectivity - many cultures consider blue and green to be shades of the same color. If you really want your mind blown, some people theorize that humans only developed a color sense recently, and that the ancient Greeks could only see the color red, as discussed here.
Again, don’t put too much stock in this stuff. Color is a science. But the combining of colors in ways that are aesthetically pleasing to humans is an art pretending to be a science. Learn these basic principles but think of them more as suggestions than immutable laws of the universe.