
Ravingdork |
Pathfinder Roleplaying Game Superscriber; Pathfinder Starfinder Roleplaying Game Subscriber

No they cannot.
It usually increases automatically with class level progression, increasing to expert automatically at 13th-level of sorcerer or wizard (see the defensive robes class ability). It never gets higher than that for those two particular classes.
Aside from the inherit +1 per level, increasing your DeX module, and enchanting an explorer's outfit with potency runes, there aren't too many (any?) ways to expedite their AC's growth rate.