I know well
Je connais bien Tom.
I know Tom well.
Je connais bien des lapins qui sont imbéciles.
I know plenty of rabbits who are idiots.
— Zootopie (2016)
I know his family well.
I know this boy well.
I know the subject well.
Je ne connais pas la pièce de théâtre, mais je connais bien l'auteur.
I don't know the play, but I know the author well.