This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 劶 is uncertain. It visually combines 后 and 力, but the original semantic or phonetic role of these components is unclear.
With no clear meaning, focus on the shape: 后 (empress) beside 力 (power). Imagine an empress exerting power, but the true meaning remains elusive.
For コウ, imagine the empress (后) giving a powerful こう (command) with her strength (力): こう -> コウ.