proceed to, assume a post
莅 centers on formally arriving to take on a role: proceeding to a place and assuming a post or position of responsibility.
莅 is a phono-semantic compound: the top 艹 (grass) suggests a position or place, while the bottom 位 (rank, position) provides both sound and meaning related to assuming a post.
Grass 艹 over a position 位: imagine a new official walking across a grassy field to take their designated seat, proceeding to assume the post.
For リ, picture a leader arriving to assume a post: leader -> リ, and the grass parts as they proceed to their position.