Yes, according to the principles of special relativity, an accelerated person traveling at a significant fraction of the speed of light will experience both time dilation and length contraction.
Time dilation refers to the phenomenon where time appears to pass more slowly for a moving object relative to a stationary observer. As the accelerated person approaches speeds close to the speed of light, time will dilate, and their clock will appear to run slower compared to a clock at rest relative to the observer. This effect is commonly referred to as the "twin paradox" because it can lead to a situation where one twin ages less than the other due to differences in their relative velocities.
On the other hand, length contraction, also known as Lorentz contraction, is the phenomenon where an object in motion appears shorter along its direction of motion compared to its at-rest length as measured by a stationary observer. As the accelerated person's velocity approaches the speed of light, the length of objects in their direction of motion will appear contracted from the perspective of a stationary observer.
It's important to note that the effects of time dilation and length contraction are reciprocal. From the perspective of the accelerated person, they would perceive the stationary observer's clock as running slower and the objects in the observer's frame as contracted in length. This reciprocity ensures that both frames of reference are equally valid, and there is no absolute "preferred" frame of reference in special relativity.
In summary, an accelerated person traveling at high velocities will experience both time dilation and length contraction according to the principles of special relativity.