それなら (sorenara) Japanese meaning: if that's the case | Kotomora、
私
も
行
き
ます
。
If that's the case, I'll go too.
If so, let's start early.
それじゃ
N3
それなら emphasizes a conditional conclusion ('if that's so') more explicitly than それじゃ, which is softer and more conversational.
それなら means 'if that's the case' and is used to draw a conclusion from a stated condition, whereas そうしたら can also simply mark a sequence of events.