40% peru, 60% palegoldenrod, in lch
For https://drafts.csswg.org/css-color-5/#color-mix
let color = new Color("peru");
color.to("lch").toString({precision:6});
let color2 = new Color("palegoldenrod");
color2.to("lch").toString({precision:6});
let mix= color.range(color2, {
space: "lch", // interpolation space
outputSpace: "srgb"
});
let blend = mix(.4); // 40% peru
blend.to("lch").toString({precision:6});