Expanding and condensing our bodies usually happens subconsciously - depending on our emotions.
However, we can expand and condense consciously by focusing our attention. You can learn a special meditation on the conscious control of our expanding and condensing body.

We can expand and condense practically the whole body; however, the most significant ability to expand and condense is a fascia*.

 Expand

The quality of Expansion makes our tissue (especially fasciae) larger or more extensive.

Direction to expand:
1) From the ground to the sky.
2) From the centre to the periphery or away from the body. It could be from the core, ming men, knees, etc., towards fingers and toes.
3) 90° from the bone to the skin surface or further.

Condense

The quality of Condensing makes our tissue (especially fasciae) denser or more concentrated.

Direction to condense:
1) To the ground.
2) From the body's periphery (or space around) to the centre. It could be from fingers and toes towards the core, dan tian, etc.
3) 90° from the skin surface, hairs (or space around) to the bone.