Is your left lung is smaller than right to make room for heart?

Yes, the left lung is smaller than the right lung to make room for the heart.

The human heart is located slightly to the left of the center of the chest and is mostly positioned between the lungs. To accommodate for the heart, the left lung has a cardiac notch where the heart rests. As a result, the left lung is smaller in size and has two lobes—the upper and lower lobes, while the right lung has three lobes—the upper, middle, and lower lobes.