Not exactly. Second layer transactions sit on top, so the hard max of 4200 "settlements"[1] in a block does not necessarily mean 4200 transactions.

With enough people using the second layer network, each "settlement" could mean finalising hundreds of transactions for thousands of people. This second layer network acts like a caching layer, and consolidates many transactions into a single transaction (put into very simple terms).

[1] Combinations of inputs and outputs.