Critical hits and enhancement bonuses.

[DRAKHOX]

Greetings, one question, do the enhancement bonuses of magic weapons (+1 to +5) multiply with critical hits?

[Diego Rossi]

Yes, they are.

CRB wrote:

A critical hit means that you roll your damage more than once, with all your usual bonuses, and add the rolls together. Unless otherwise specified, the threat range for a critical hit on an attack roll is 20, and the multiplier is ×2.

Exception: Precision damage (such as from a rogue’s sneak attack class feature) and additional damage dice from weapon special abilities (such as f laming) are not multiplied when you score a critical hit.