Using a potentiometer to control greater resistance
Generally not. You could switch in series resistors to the combination to make the rheostat a &quot;fine&quot; adjustment control but that requires switches which are out of scope.
One of the practical problems you would encounter is that the power dissipation of the pot may be exceeded at low values. Remember that the power rating is for the whole track. If you use only a fraction of the resistance track then the maximum power dissipation decreases to that fraction of the pot's power rating. Think of it as power rating per unit length or per degree of rotation.