Literary techniques is a pretty broad term. I'll give you several examples of different types that can contribute to the development of a theme:
Characterization: the art of creating a character through the speech and actions of him/her and others
By developing a character like Julia (the Dark Haired Girl), Orwell shows us the type of character who would rebel against the society in Oceania, pointing out its flaws and illustrating the type of person who actively and consciously chooses to not fit in.
Symbolism: the use of a physical object to develop a secondary, physical meaning that accompanies the first literal meaning
The glass paperweight, which contains a fragment of coral, symbolizes beauty and the past. The fact that both of these things are rejected by Oceania is significant because Winston chooses to keep and value this object despite the fact that owning it is a factor of rebellion.
Diction: the word choice an author uses to develop tone
Orwell's word choice when describing Winston's behavior and perspective is laced with fear, criticism, and confusion. His observations of his society develop a tone that invites the reader to agree with Winston, thereby developing this theme.
Conflict: the driving forces that develop the plot of a story and pit the protagonist against a variety of other people or things
One of the main conflicts in this novel is Person vs. Society, which develops the theme of rebellion because Winston, the protagonist, cannot agree with the values and rules of his society.