Historical / Isekai / reincarnate BL I:
https://www.mangago.me/home/mangalist/835803/
Historical / Isekai / reincarnate BL II:
https://www.mangago.me/home/mangalist/1594530/
Isekai BL
Reincarnation, Transmigration
Reincarnated in Another World
Reincarnated in a Game World
Reincarnated in a Book World
Transported to Another World
Reincarnated Lover
Multiple Reincarnation
Reincarnated in the Past
Time Travel
Time Rewind
Part 2:https://www.mangago.me/home/mangalist/3123306/
Contains all old man and middle-aged man BL I could ever find. All of these guys are 35+(I know 35 year olds are not old men, but according to BL standards, they are). Mostly contains BL with old ukes or both of the guys are old men. There are some with old man semes as well, but it depends on whether I read them or find them.