Does a defendant have to forfeit his Sixth Amendment right to request a jury trial to determine the length of his sentence?

Lewis maintains the trial court's imposition of a de facto LWOP term violated the Sixth Amendment because he was deprived of his right to have a jury, rather than a judge, make the finding allowing for an increase in his sentence beyond the statutory maximum. He acknowledges that irreparable corruption is a constitutionally required finding, rather than an element of any crime required by the legislature. But he contends irreparable corruption should be treated as a "necessary finding" that is functionally the equivalent of an element of a greater offense. We address the argument despite his failure to assert the issue below. (See People v. French (2008) 43 Cal.4th 36, 46-48 [defendant did not forfeit Sixth Amendment rights by failing to request jury trial on aggravating circumstances].)