Yes, according to Einstein's theory of relativity, if two observers meet, synchronize their clocks, and then one of the observers travels away at a significant fraction of the speed of light and returns, there will be a time difference between the clocks of the two observers.
This phenomenon is known as time dilation, which is a consequence of the theory of special relativity. Time dilation occurs when there is relative motion between two observers, and it means that the passage of time is experienced differently by each observer.
From the perspective of the observer who remains at rest, the moving observer's clock will appear to be running slower than their own clock. This means that less time will have passed on the moving observer's clock compared to the stationary observer's clock when they meet again.
The time difference between the clocks will depend on the speed of the moving observer relative to the stationary observer and the duration of their journey. The closer the speed of the moving observer is to the speed of light, the greater the time dilation effect.
Experimental evidence has confirmed the predictions of time dilation, such as through high-speed particle accelerators and atomic clocks on fast-moving objects like satellites. These observations have demonstrated that time dilation is a real effect, and it is an essential aspect of Einstein's theory of relativity.