This list compiles hot older males in different genres, could be yaoi, could be straight, it doesn’t even have to be a romance. Also include cute ojisans as well. The ages are middle-aged to silver foxes. some might be just older lovers but the feels are similar. Some could be sad or some could be happy go lucky. I say ossan and ojisan but I will also include onisans. Don't worry about age too much if they older they will be included.
List #2
https://www.mangago.me/home/mangalist/1790712/ 
Bi No Kyoujin: Smoke