I’s sorry, I was not specific enough when I said “reflectors”. Certainly aluminum reflectors around the COBs will do exactly what you said in terms of the inverse square law. But I was talking about making side walls out of flat white painted cardboard to shrink a tent that’s too big. Those are technically reflectors too. They just reflect the light that would normally go off towards the tent walls and end up on the ground, onto the plants instead. Light on the ground does no good. Those cardboard pieces can be tilted back so they admit all the light and in toward the pot or pots at the bottom to make the plant get the reflected light instead of the floor.
This is a way to defeat the inverse square law to some extent, and I have measured it in my grow chamber with a lux meter. Near the bottom of the plant I see more light coming in from all four side cardboard reflectors than is coming directly from the lights. Like 30000 direct and 4 x 10000 from all four side reflectors.