Moore's law states that the technical innovations are being absorbed already. The device's controllability has dramatically improved since moving from a straightforward metal oxide semiconductor field effect transistor (FET) constructed with a single control gate to one with many control gates. Here, the device-level simulation of vertically stacked GAA nanosheet FET is performed, for which the various geometrical variations are calibrated to examine the impact of these geometrical variations on the device's performance. The most prominent parameters like ION, IOFF, SS, DIBL, switching ratio, and threshold voltage values are analyzed. For the device to be considered to have better performance ION should be maximum, IOFF should be minimum. Hence, to obtain this, the thickness of the nanosheet is varied on the scale of 5 to 9 nm, and the width is varied from 10 to 50 nm. The device simulation and analysis are performed using the Visual TCAD - 3D Cogenda tool.