Zelda's Golden Horse Side Adventures

In-game Description

Penn’s research at Snowfield Stable turned up a story about Princess !Zelda’s golden horse, which has a mane braided with honeycomb plaits. It was being kept there but ran off somewhere to the north.
Harlow can’t go look for the horse, given that a huge monster is apparently in the snow fields

Note: Must have spoken to Penn at the Lucky Clover Gazette stables near Rito Village before you can begin this quest.

The Golden Horse can be found in the North Tabantha Snowfield, past the Frost Gleeok who guards the ruins. He is stood with a group of three other horses by a large, broken ruins. See https://www.gamerguides.com/the-legend-of-zelda-tears-of-the-kingdom/maps/hyrule-surface-map#42801 for its location.

Be sure to have at least 1.5-2 Stamina Wheels full to tame him. Once tamed, ride him back to the Snowfield Stables and speak to the stablehand to finish the quest. You can then register him with the stables to use as your own!

After completion:

You found the golden horse, and Harlow was beside herself when you returned the gentle creature to the stable. She asked you to take the horse, as it already seems attached to you. Penn flew off to write the whole story up for the newspaper.