You produce a hundred 24 core cpus, then you test them rigorously. You discover that 30 work perfectly and sell them as the 24 core mdoel. 30 have between one and eight defective cores, so you block access to those cores and sell them as the 16 core model. Rinse and repeat until you reach the minimum number of cores for a saleable cpu.

Except the ratios of consumer demand do not always match up neatly with the production ratios. IIRC there have been cases where they've overproduced the top model but expected not to be able to sell them all at the price they were asking for that model, and chose to artificially "cripple" some of those and sell them as a more limited model. An alternative sales strategy would have been to lower the price of the top model to increase demand for it, of course, but that may not always be the most profitable thing to do.