Qué te bajes de su caballo alto
Does it make sense? You get off your high horse!
"Get off your high horse" means to get humble. But it does not translate into Spanish. "¡No seas arrogante!"
Similar expressions have very different meanings:
"Bájate de esa nube" - quit daydreaming
"Bájate de la mula" - start paying what you owe.
There is an expression: "To get on your high horse"
(I am not aware of one that says 'to get off your high horse')
= ponerse muy arrogante
Se puso muy arrogante
= He got on his high horse
I hope that this helps
This made me so curious I searched and found some ideas: Deja esa actitud altanera Basta ya de soberbia and then this one which sounds like it just might be a straight translation but I don't know bájate de tu pedestal