There's still a quality of rough edges with Alcaraz. Woe to the rest of the tour if he manages to smooth them out
and retain his ferocity. The point being, I still think he could improve. Jannik, I think, is maxed out - or close to it.
So I wouldn't dampen expectations in that Carlos can win literally any match. But if you think he'll win
every match, then sure

.
As for quickest to five Slams:
Nadal (b. June 3, 1986) - 2008 Wimbledon (final on July 6, 2008). 22 years old, 1 month and 3 days.
Alcaraz (b. May 5, 2003) - 2025 Roland Garros (June 8, 2025). 22 years old, 1 month and 3 days.
Given that June is one day longer than May, I believe Alcaraz was one day younger than Nadal. Someone can check my math, though.
Oh, and...
Borg (b. June 6, 1956) - 1978 Roland Garros (June 11, 1978). 22 years old, 5 days.
So Borg was younger than Nadal and Alcaraz by about three weeks.