No. Criminals can be reformed or rehabilitated.
Will he ever learn some manners?"Can he reform or rehabilitate himself into a good person"
Is he capable (at all) of learning some manners, or is he a lost cause?"can he be reformed"
What's the best way of teaching him good manners?"what is the way to reform this ill mannered person"?
No, see suggestions below.
Will he ever learn some manners?
Is he capable (at all) of learning some manners, or is he a lost cause?
What's the best way of teaching him good manners?
Can we say "can he reform himself" for "a criminal" or "an ill mannered person?"
Not really, since reformed almost always has the meaning of 'by another person, group of people, or thing'. Also, follow it with the preposition into, not to.