This button will help reset all transform values ​​of the object to its original value. For example, the object's location will reset to coordinates 0,0,0

First, please download the Zip file of this add-on. Then, open Blender, install it by clicking on Edit, Preferences, Add-ons. Click 'install' and select the Zip file you just downloaded. Activate it, and this add-on will appear in the viewport sidebar (Press shortcut N to open viewport sidebar). 

This button for applying the object's transformation to its original data. That means the current transform of the currently selected object will become the default transform of the object when you reset transform values ​​to 0

In computer graphics, level of detail (LOD) refers to the complexity of a 3D model representation. LOD can be decreased as the model moves away from the viewer or according to other metrics such as object importance, viewpoint-relative speed or position. LOD techniques increase the efficiency of rendering by decreasing the workload on graphics pipeline stages, usually vertex transformations. The reduced visual quality of the model is often unnoticed because of the small effect on object appearance when distant or moving fast.

LOD helps to manage the computational requirements of rendering complex scenes (essentially reducing the file size/amount of data of the 3D model), allowing for smoother and more efficient performance while preserving visual quality.