Litaray techniques can convey all types of meaning such as using allegory in The Crucible, to convey the message of Communist Prosecution during the McCarthy era.
Can't be bothered writing a long post. I'll give you one technique. One is the use of a motif. A motif is a recurring element in a novel, which may act as a symbol to convey the theme. If it pops up all the time, the theme is being emphasised.