Albert Einstein's theory of general relativity predicts that where gravity is stronger, time passes more slowly. That's called time dilation. Gravity is stronger closer to the center of the Earth. So, according to Einstein, time should pass more slowly closer to the ground. (And experiments have confirmed this.)
More, same source:
The force of gravity treats time like taffy. The stronger its pull, the more gravity can stretch out time, making it pass more slowly. By using a new atomic clock, scientists have now measured this slowing of time over the shortest distance yet — just one millimeter (0.04 inch).
https://www.snexplores.org/article/a-new-clock-shows-how-gravity-warps-time-even-over-tiny-distances#:~:text=Albert%20Einstein's%20theory%20of%20general,slowly%20closer%20to%20the%20ground.