One of the cool things about some of the long kunyomi readings, though, is that they are actually just phrases that have been mashed together, as discussed here.
Of course, some are easier to see than others. 志す (こころざす) coming from 心 and 指す is easier to imagine than what 企てる came from.
The origin of 企てる is from a classical Japanese word くはたつ, where くは meant the arch of your foot (this word doesn’t exist anymore in modern Japanese, and that part of your body is now called the 土踏まず), and たつ is 立つ. Here, the 立つ doesn’t mean that you stand on the arch of your foot; it means that you raise the arch of your foot straight up. In other words, you’re on your tiptoes.
If you’re on your tiptoes, you are usually trying to see farther. This was metaphorically extended to planning. So that’s how we ended up with the verb くわだてる, and it was assigned a single kanji that means “plan.”
Not really all that helpful in the moment someone is learning the word for the first time, but I found researching it to be interesting.