So I have a a usb with tails and an encrypted persistent volume. However, im wondering should i encrypt the whole usb with veracrypt or is this not needed? Also, if i did this would the computer just ask for the pass phrase before launching tails when i boot from USB?
If you have a persistent volume, encrypt it is a safe bet.
However, you can't use it Veracrypt since it won't ask you the passphrase at the boot. You can use a LUKS encryption. Google it and you'll find some tutorials for Tails