For example, a red circle on a green background pops a bit more than a blue circle on a green background. But a blue circle will look a lot better and more obvious on an orange background.
So if you’re using a predominantly green website, it’s a good idea to implement red calls to action, or use red to highlight important features that you want to catch the eye of any readers.
Try to only have one or two colors on top of your primary color. More than that, and you’ll be struggling with clutter. Nothing will stand out well if you inundate visitors with loads of different stimuli.
A good example of using additional colors is hearing aid brand Eargo. It has a main color of orange, so it’s used this duller blue to highlight this important section of its website. From what we know about color compliments, we can see how this blue and bright orange contrast against each other. The orange also makes important elements pop, like the “add to cart” button and the logo.