what would you produce if you breed a mexican red knee tarantula to a chilean rose tarantula?

For the love of God and all that is holy do NOT ever produce hybrid tarantulas. That is always a disaster for the entire hobby when they get bred and sold, mislabeled and completely ruin the genetic integrity of species involved, in addition to inducing deformities. It's happened once before; please don't let it happen again.

They aren't related so it won't work, but if it did then how about an Aztec Rosy Red Tarantula

Absolutely nothing would happen, as they cannot interbreed.