So I was getting the giant horse, as usual, in BOTW post-game on my all shrines save file, and then while I was getting it to the nearest stable to register it, it got killed by a Lynel. Will it respawn? I already tried the horse fairy. It didn’t work because it wasn’t registered. I think I may have tried a blood moon, but it wasn’t there. Is there any way to get it back without restarting my save file?
It appears that all horses will eventually respawn in the local areas where they are originally found, just based on other players' experience.
From a GameFAQs thread:
I confirmed that you can release the giant or white horse then find them again in their respective places.
And another GameFAQs thread:
So I released [the giant horse]. Then I checked if it respawns in Taobab Grassland and yes, it does (what a relief).