Contrast, as the name implies, is about finding totally different, but still complementary typefaces that are each fit for their intended application. Traditionally, this involves pairing a serif with a sans serif. Typefaces will generally conflict if they are too similar: two ever-so-slightly different serifs or sans serifs rarely play nicely together.
As a designer, the important thing is to establish a clear hierarchy. This could be as simple as varying size and weight of the same typeface, but where the typeface varies, that’s where careful pairing is crucial. If you have a display face packed with unique personality, you’ll need something more neutral to do the hard work.
This is a great article from Creative Bloq if you’re trying to find some good font combos…
https://www.creativebloq.com/typography/20-perfect-type-pairings-3132120