What the OP suggests hardly makes any sense. The whole point of these offers is at the moment of their offer. You have to see the match and the offer and make a decision based on that. If you choose to withdraw x2 in advance, then the whole point of gambling is lost.

But the OP's idea gave me another idea. What if online casinos introduced the auto-withdrawal functionality if a player reached a specified x of their deposit. We all know how hard it is to stop when you catch a winning streak. And very often we end up losing everything. What if there was a feature that would allow you to automatically withdraw your balance if you reached x2, x5, x10 of your deposit? Would you use such a feature? Maybe there are already casinos that offer this? Please share your thoughts