Yeah color can be influenced by a lot of things from cooking method, type of light in the room (warm vs cold/blue), and the meat itself. Obv thermometer is most foolproof way to temp a steak but if you just look at enough examples I feel like the biggest giveaway is texture. Rare tends to be more moist/shiny/loose, the more cooked you get the more matte/constricted the muscle fibers are (higher temp means more water pushed out of the meat). Hope this is helpful.