Do you want recommendations where this happens within the main relationship? As in, are you looking for bl where there are scenes of the main couple where the top tops then switches roles later on?
If you want what I described earlier where it's within the main couple, I highly recommend this list:
https://www.mangago.zone/home/mangalist/68441/
I've read stories off of it!.
I'm sure you've already heard of the story Neko x Neko as well, but it not, while it focuses on a bottom topping, it does ALSO show the perspective of the top who bottoms as well!
But if you want stories where the top tops other people but once they find ML, they bottom in the bedroom, you can refer to.this list instead:
https://www.mangago.zone/home/mangalist/656956/
I have read a few off this list so you should be able to find some here if you only want top who tops others trying out bottoming once he gets in the main relationship,
Read this recently and really liked it!
https://www.mangago.zone/read-manga/nidome_ha_shoujiki/
thank you!
any recs of bl that the top becomes bottom??