Both of those are extremely basic z-drags, but show the principle well.
When using biners instead of pulleys some of the mechanical advantage is lost to friction.
I prefer to use prussiks so you can pull as far as needed, sliding the prussiks up the rope and pulling again.
I also prefer to use another pulley at the anchor so the pulling can be done parallel to the river instead of perpendicular to it.
The set-ups shown also have no braking device, to hold the line where you pulled it to. A figure "8" device is typically used on the anchor to perform braking via a second rope and prussik.
The "Z" can be repeated for even more pulling power, say for a wrapped raft.
Always stay on the upstream side of any rope!
A come-a-long is also a handy ay to unwrap a boat, although a bit heavy for a kayak, but easily carried on a raft.
A z-drag can also be use for getting a vehicle unstuck, dont ask me how I know this