When I read Sharon VL's reply on the other thread about this, I suspected that the three-size limit was in all stand-alone versions of LR, as another way to encourage those of us with older eyes to sign up for a CC subscription. However, I just checked preferences in my stand-alone LR 6.5, and indeed there are the five sizes Sharon mentioned, plus "auto."
What version of LR do you have, Ellis?
-Eric