There isn’t a combined package like there is on NCL. As others have said, you can prepay gratuities at the time of booking if you wish. You can also prepay for a drinks package (which will
include gratuities). The price for the drinks package isn’t set and can change by sailing, but seems to be between $65-80 per person per day based on prices people have paid. There are regular offers such as x% off or buy one get 50% the second etc. you can buy and then cancel and repurchase if the price goes down.