I have tried by assigning winding with no. of turns as well but there is no variation in the L value with small metal object as shown in screenshots above. However, when I am using a flat plate covering the entire coil as shown below, there is variation in L value. So, isnt it weird that for a large plate, there is variation in L and not with small coin like object both made of the same material, i.e. copper?
If you want my model, I can share it too.