Hidden inside a cave found at the top of mount Shann in Red Dead Redemption 2, players can find the Giant Remains, which likely belonged to Squatch Bigfoot.
Other than finding these remains, players can do little else, as there are no other similar being alive in the area. It is, however, possible to speak with a giant in the game, a giant that's likely another Bigfoot.
Before you can talk with the Red Dead Redemption 2 giant, you need to have studied at least 30 animals. You can do so by hunting them or by simply pressing the L2 or left trigger buttons while an animal is in the vicinity. If you're attempting to discover this Easter Egg during the late game, it's likely that you have studied way more than 30 animals.
Once you have cleared this requirement, you need to head to the east of the Wapiti Indian Reservation, located to the north of Bacchus Station. Get near the river to spot several Alpine goats. As soon as you get to the location, a flock of birds will fly away. Follow them until you reach a mountain.
Continue proceeding on the small mountain to see a cave blocked with a rock on your right. You will hear a voice greeting you, and you have to interact with it immediately to continue talking with the mysterious creature. He will give Arthur a description of how he looks like.
If you wish to further engage with this creature, you can come back to the same spot after three days to learn more about him. He will talk more about himself, and how big he is. He will also tell Arthur that, sometimes, he longs to have a wife, but he always changes his mind due to how cruel women can be and how no one wants large children, as they eat too much. Another clear hint at the creature's size.
After you have talked with the creature a few times, he will have told you everything he has to, and you will have done everything you can to discover this Easter Egg.