Is there any idiom in English similar to
Horse as boy, (brave) man as kook (are best).
in which boy means sorrel. The latter is obvious.
It is my translation(maybe it is wrong) to describe the idiom I’m seeking.
“Do not be afraid to insist on your rightful case. You should know that a good horse is called sorrel, and a good young man is called crazy (brave, fearless, and bold).” (source)
Sorrel horses are more imposing, more muscular and stronger than other
horses. More powerful and warrior riders ride on horses. More powerful
and warrior riders ride on horses. The horse is the best, the brave is
alive and kicking(that is, powerful and attractive). They call them
unflinching, a bit stern(badass), strong, and fair, brave. Since the
power is money in the current period, we can compare the horse to the
car and the power of the valiant to money.
The horse mentioned here is powerful, strong. And the horse possessing the features is sensed as best horse among the horse species. In the same way, a person behaving differently(may be eccentric) while solving problem, evading issues in a genius and tricky way and smartly is sensed as best.
Atın dorusu, yiğidin delisi makbuldür.
You are translating, so you may need to be inventive. Idioms rarely translate directly and invention is an okay thing.
Your idiom is originally Turkish. In English culture, we respect the stallion as a kind of wild, handsome, hard to tame horse that pretty much fits your description of the man. “Stallion” even applies directly to people in the same good way you mean.
The full meaning is all wrapped up in that one word, if used as a metaphore and not a simile. If you need a two-part proverb, consider creating one. Here are two I thought of just for you…
An able-minded boy starts as a bronco, but grows to become a stallion.
A strong horse is a Belgian, a strong man is a stallion.
It is worth noting that in English culture, the Belgian is more commonly known than the sorrel, but you could use “sorrel” instead of “Belgian” if you must.