Not necessarily.
(Not that I want to give any credence to the concept of an omniscient entity of any sort, but...)
God may see all futures, thus he knows each one of them, and can freely experience all of them simultaneously, yet still have the power to choose a single one of them for us poor mortals to experience.
If I were going to conceive of an entity free from the constraints of time, that is how I would do it. It would only be a human shortcoming to think in terms of a single "the" future.
Then the 1 god chooses is the only 1 that happens. God may see all conceivable futures but only 1 will happen. If god knows which 1, that is the 1 that happens.
Not certain what is meant by constraints of time. No entity which changes or does anything or anything happens to can be without time. Nothing can happen without time.
<>