dress up
妝 centers on the act of adorning oneself, especially through clothing, makeup, or accessories. The single given meaning 'dress up' captures this idea of deliberate personal decoration.
妝 combines 爿 (a bed or couch) with 女 (woman), suggesting a woman at her dressing table or a scene of personal adornment. The exact historical development is uncertain, but the components point toward the idea of dressing up.
A woman 女 beside a dressing table 爿, carefully putting on makeup and adjusting her clothes to dress up.
For ソウ, imagine a woman dressing up in a beautiful silk robe, tying the sash with a soft 'sow' sound as the fabric slides: sow -> ソウ.