I think that, at certain times and with certain baits, that can be true.
Since there is usually a variation in the sizes of prey species in most lakes and rivers, going to a larger lure can make the lure stand out enough to make it attractive.
In the case of crawdads, small bass won't take on a big craw, but big bass will.
And if your lake is stocked with trout, or has larger bait fish, like the Hitch in Clear Lake, adult bass get accustomed to foraging on the larger bait, since one big trout meal is less work and more calories than fifty small shad.
When bass are chasing bait, and busting them on the surface, they can be really size specific. But, even there, the bigger, more experienced bass may be below the bait that's been forced to the surface, waiting for the stunned "sloppy seconds" to drift down to them. It's an easier, calorie cheaper meal.
I find a full sized 6" Senko in the purple/white laminated color, dropped down through the busting fish rigged wacky style with a circle hook, often gets the bigger bass that are under the bait, even though it's much bigger than the shad or silversides that are being chased.
I've also had eight inch bass eat a 10" worm, so it's not a hard and fast rule, but it is often the case for me.