Questions & Answers about Yoğurt soğuk.
• soğuk yoğurt = “cold yogurt” (just describing which yogurt)
• Yoğurt soğuk = “Yogurt is cold” (a full sentence stating its temperature)
You can attach the copula‐suffix -dur (or -tir, -dür, -tır depending on vowel harmony) to soğuk:
• Yoğurt soğuktur.
This is more formal/written. In everyday speech you’d still skip it.