Sodium restriction leads to a dose-dependent reduction in blood pressure across varying dietary patterns, with the greatest reduction observed in individuals who have elevated baseline blood pressure.

Study: Effect of dose and duration of reduction in dietary sodium on blood pressure levels: systematic review and meta-analysis of randomised trials

This study found that the less salt people eat, the lower their blood pressure goes—and the higher their blood pressure was to start with, the more it drops. This matches exactly what the claim says.

Study: Blood Pressure Effects of Sodium Reduction

This study found that eating less salt lowers blood pressure, and the less salt you eat, the more your blood pressure drops — especially if it was already high to begin with.

Study: Effects of Sodium Reduction and the DASH Diet in Relation to Baseline Blood Pressure.

The study found that eating less salt lowers blood pressure more in people who already have high blood pressure, and the less salt they ate, the more their blood pressure dropped — exactly what the claim says.

Study: Associations Between Salt‐Restriction Spoons and Long‐Term Changes in Urinary Na+/K+ Ratios and Blood Pressure: Findings From a Population‐Based Cohort

People who used a special spoon to put less salt in their food ate less sodium, and their blood pressure didn’t rise as much—especially if they were already eating a lot of salt. This proves that cutting back on salt helps lower blood pressure, especially when you start with high levels.