As mentioned temperament is up to cockerels. We've had some accidental ones that were okay. Some were not good.
We kept a boy this year, buff Brahma, and knew he'd take longer to "act up". We raised them under our two year old hens.
When he started maturing/hormonal behavior, he went in a pen within our run. That way he was still with the flock but not with them.
After a month we let him out. He was doing decently, checking boxes, calling for feed. But started standing on the girls after mating and not moving, sooo back into timeout he went. He is still young and still learning. He was 5.5 months when he started and by August will be a year old.
We plan on releasing him then when we separate our broodies chicks by then. And hopefully if he keeps up his good behavior, we have a good feeling about this one. He's never showed us any aggression, my kids are near adults and taller than me, so that's not a worry either.
They can be a crap shoot, but once you get past the hormone teenage stage is when (I've read) they start to behave towards the girls.
Hope this helps? Good luck