One base color and five schemes, each computed as hue arithmetic: on the OKLCH hue circle with oklch(from var(--base) l c calc(h + N)), and on the HSL wheel that most color-wheel tools use.
Relative color syntax: checking…
Monochromatic: one hue, lightness ± 0.1 and ± 0.2
Tints and shades of the base. On the OKLCH wheel the steps are even; HSL's lightness steps are not what the eye sees.
Analogous: h − 30, h, h + 30
Neighbors on the wheel: calm, and easy to hold together.
Complementary: h, h + 180
Opposites: the strongest contrast of hue, best as a main color and a small accent.
Split-complementary: h, h + 150, h + 210
The complement's two neighbors instead of the complement: nearly as lively, less harsh.
Triadic: h, h + 120, h + 240
Three hues evenly spaced: lively, and hard to balance without one leading.