Post paid account require. Tax will be added while placing order and activation will be charged depends on new line or upgrade.
If you cancel with in 3 days , no activation charges.
If you pay total upfront , no amount will be financed with Verizon so you can call as soon as you picked the order or as soon as it ship , to cancel the line . Verizon will do it without any issue as they will see no payment due.
You will be able to trade the device against Fold 6 for same amount or more during launch offer.