method:
(ppt23 edition) menu bar, "format"-> "Slide Design" or "Slide Show"->; Animation scheme, a new window pops up on the right, and there are three links vertically arranged on it: design template, color scheme and animation scheme
top left: monochrome (different lightness of the same color)
top middle: adjacent color
bottom middle: complementary color
bottom right: double complementary color.