As part of a prenup, your future spouse can agree to make a will or trust, or waive certain death benefits regarding your property, to carry out the purpose of the agreement. The prenup will be binding if the other party tries to change their will in the future.
One of the purposes of a prenup is to guarantee that you retain control over your premarital property. This is especially important in cases where one party has children from another marriage and wants to ensure the children are entitled to certain property instead of their new spouse.