and, along with, reach, extend to
曁 centers on connection and inclusion: joining things together, accompanying, or reaching out to include something. The meanings 'and' and 'along with' express simple conjunction, while 'reach' and 'extend to' describe the act of stretching toward or encompassing something.
曁 is a rare character whose exact historical development is uncertain. It appears to combine 旣 (already, since) with 旦 (dawn), but the semantic contribution of these components is not clearly established.
The top part 旣 suggests something already present, and the bottom 旦 is the dawn sun rising. Picture the sun's rays reaching out to join with the existing landscape, extending to include everything in its light.
For キ, imagine a key that unlocks a door, allowing you to reach through and join what's on the other side: key -> キ, and the key extends your reach.