Interaction in virtual reality (VR) is often constrained by physical limitations, such as the user's physical space and body's range of motion. In this study, we propose a novel hand redirection technique using dynamic changes in the size of the virtual hand and evaluate its effects on detection thresholds and operability. Experiments involved interactions by moving virtual hands between objects while completing 2AFC tasks assessing the normalcy of redirected displays, and results showed that dynamically increasing the size of the virtual hand during depth movement extended the detection thresholds, allowing users to continue operations without discomfort. In addition, size changes contributed to the extension of detection thresholds in horizontal and vertical directions, although the effects varied by direction. However, excessive increases in size reduced the sense of body ownership, potentially compromising usability. This may potentially contribute to the efficiency of the user interface in VR and the extensibility of rehabilitation for large movements. This research highlights new features of body perception in VR and provides guidelines for designing more intuitive and flexible VR interactions.