lean on
靠 centers on physical reliance: leaning on something for support. The given meaning 'lean on' captures this idea directly.
靠 is composed of 告 (announce, tell) on top and 非 (not, wrong) on the bottom. The historical development is uncertain, but it may have originally combined a sound element with a semantic element related to leaning or depending.
Imagine someone announcing (告) that they are not (非) able to stand on their own, so they lean on a wall for support.
For コウ, picture a person leaning on a coat rack: coat -> コウ, and the rack supports them as they lean.