Peace in this collection has more than one direction. Some passages quiet a frightened person; others ask that person to make peace with someone else. That distinction matters: inward calm and repaired relationships can support each other, but one is not evidence that the other has happened.
Start with Isaiah 26:3 for steadiness of mind, Philippians 4:6 for prayer in anxiety, or Matthew 5:9 for the active work of peacemaking. Read the nearby verses before treating any one line as a technique or guarantee.