Once you find it, you want to slowly get in range of the White Arabian until you can hold L2/LT to focus on it. Once you’re ready, crouch and start moving towards the area, using Eagle Eye (元 + R3) when possible to spot heat signatures from afar. To my knowledge, you only get one shot, so you want to be very prepared before you attempt this. It’s easy to put a foot wrong and lose the horse, and it’s not guaranteed to return if you frighten it off. At this point, you should save your game manually to make sure you have an instance to return to if you mess up.
I’d recommend you dismount a good distance away from the spot marked there so that your current, inferior horse doesn’t scare the White Arabian and make it bolt. Put on your best Winter Gear to mitigate the weather so you have enough stamina and health to tame it, and head to the western bank of Lake Isabella, as marked on the map above. Its white coat masks the horse amidst snowstorms, making it particularly hard to spot. The White Arabian is an elusive creature that hides out in the tundra of the West Grizzlies.
