How much did you earned through esops via IPO?

Primarily, my question targets startups which went ipo where you may joined when it was a private company and later it went public and you liquidates it.

• will your esop units gets multiplied before ipo?
• will exercise price gets increased before ipo?
• what about the tax?
• are there any unknowns and nuances involved which you were not aware of and later realised? I hold esops in a startup and want to understand how this works during an IPO