I can’t imagine all those billions of transistors and wires being plotted manually one by one by people

They don’t really need to be cause it’s a repeating pattern.

Doesn’t matter what the pattern is, but think of it like a checkerboard.

If you were making one, you’d take the time to just draw it yourself. This would be designing a chip.

If you decided to cover a football field in checkerboard battery, you’d take you’re existing pattern, and just “stamp” that over and over again. Maybe even strap a dozen checkerboards together and then stamp that. This would be scaling your initial chip design for producture.

Once the entire design is done, you make some prototypes, test them, and fix fail points.

When you go in wide scale production, some have too many errors, so you blank out even more and sell it for cheaper. Although that’s out of scope it’s good to highlight that there are acceptable fail rates for design. If they went only for 100% success nothing would ever make it to production