pressure
壓 centers on the idea of pressing down or applying force from above: pressure, pushing, or holding something down.
壓 is the traditional form of 圧. It combines 厭 (which likely contributes the sound) with 土 (earth), suggesting pressing earth down or applying pressure from above. The modern simplified form 圧 replaces the complex upper component with a simpler shape.
The top part 厭 looks like a heavy, oppressive structure, and the bottom 土 is earth. Imagine a massive weight pressing down on the soil: that is pressure.
For アツ, picture a heavy anvil pressing down: "ats!" is the sound of the pressure being applied. Ats -> アツ.