I want to read a romance shoujo manga about a girl who's always happy and cheers people up. I want her to help anyone who needs her help even if it means rushing into danger. The main guy falls in love with her because she's brave, loyal and very kind. He doesn't have to fall in love or realize his feeling right away. I want the guy to be some sort of rich leader type person. Like he's a king or a president of a company or something like that. If you could find something like this I would really appreciate it!

Sora wa Akai Kawa no Hotori
Akatsuki no Yona
Fushigi Yuugi - Genbu Kaiden
Basara
Bara no Tame ni

Akagami no Shirayukihime fits your description perfectly. The female lead is cheerful and helpful. The male lead is a prince.
Fruits Basket fits the female exactly, but not the male. His family is wealthy, but he's not in a position of power.
Hope one of these works 🙂