This is parallax using perspective on the overflow element. The perspective origin is outside of the scroller so it stays in place while you scroll down and the parallax elements move up.

This means to make a parallax element not move it would have to be infinitely far away.

▼ perspective origin (the scroller element)

This is parallax using position sticky. The perspective origin is inside the scroller so it moves up as you scroll down but the sticky parallax elements are stuck so they try to stay in place.

To make a parallax element move 1:1 with the scrolling content it would have to be infinitely far away.

▲ sticky perspective origin (top of scrolling contents)