Question: red dead redemption 2 how tame horse?
Answer: Chase down the horse you want to tame and lasso it. It's easier to do this on horseback.
Once lassoed, continue to hold [L2 / LT] and press [Square / X] to Calm the horse.
When you're close, jump onto the horse's back. ... 
Move [Right Thumbstick] to stay on the horse until it gives up.