According to Black Out 2022 Sapper Morton was incepted (birthed) in 2019. By the time of Blade Runner 2049 his actual age is 30, Wallace having long since solved the problem of short replicant lifespans.
We've see other replicants being decanted as full adults, so there's no good reason to assume that this wasn't the case with him and his fellow combat models.
Notably, Villeneuve had his character pegged as being in his 60's, which suggests that he was decanted at a relative age of around 30.
Dave Bautista was recruited to play the old Nexus model, made for hard
labor, war, and battle. “I needed someone who could play a giant, but a gentle
giant,” recalls Denis Villeneuve. “Sapper needed to be benevolent, but also
potentially very dangerous. Dave gave the character a sense of melancholy
and vulnerability, so when you first see him, you feel empathy for him."
Bautista wasn’t an obvious choice for the role, however. The character was
written as a 60-year old Replicant, but Dave Bautista was much younger.
“I flew out from Atlanta to meet Denis Villeneuve and right off the bat he
tells me, ‘I hate to tell you, but you’re too young for this role.’ Through my
experience in Hollywood, I’ve been told I’m too big or too old, never that
I was too young.”