Is there a way to replace an object in my scene with a different one? Is there a way to replace one object position to another object position? and automatically match the scale? Any sort of addon or there is a way to do it? For example, I have a basic chair obj in the scene, however I downloaded a better chair, so I import the obj to the scene, is there a way I can just replace the downloaded chair obj to the basic obj with matching the scale and position?
If the objects are all of the same type (mesh, curve, empty, etc) you can use the make links menu.

Select all objects you want to replace, then Shift-Select the "master object" you want to replace with making sure it remains as Active Object.

Then press Ctrl + L Make links > Object Data.

You can also access it from the Object > Make Links > Object Data menu in the 3DView header.

If objects are empties with duplicated collections use the Instance Collection option instead.