«أنت لا تكذب»
You do not lie.
«لا تكذب أنت»
You do not lie (with potentially different stress according to context).
An initial addressee pronoun can foreground the person and reinforce the denial of the predicate. If the speaker is defending someone wrongly suspected of lying, this order may make the response especially pointed.
The basic truth claim may remain that the hearer does not lie. Word order may shift information structure and force without necessarily changing all the truth conditions. Contrastive exclusion still requires evidence from context or expression.