The amount of AI horse art is confusing. Like bro...that "horse" has 6 legs, butt for lips, and is half way in the ground. Against such amazing photographers and artist, Why even go through the process of uploading??
You'd have to worry about blending multiple stocks together, then painting over it a bit, then perhaps making a background out of several images, and then blending it all together. On a tablet with a stylus. Have some pity on yourself.
Bluey Magical horses are difficult to make. Not meaning to discourage, but maybe you should start from something like pegasus or simply a set of horns.
Bluey, mythological unicorns were carnivorous and would gore people with their horns and eat them...a unicorn like that could ne neat if you like that sort of vibe, lol