First, even constrained choices can be meaningful. Just because I can't choose to fly by flapping my arms, wouldn't mean I don't have free will. If free will exists, I can still choose among the options available to me. I don't think anyone operates by the definition of "free will" that you seem to be proposing. Free will is the ability to select from among the options you are given. The opposite of that would be that you'd always make the same pick every time, because your decisions are actually the results of forces acting upon you. If you had the choice between red, green, and blue; you'd choose red every time if we could rerun your life up to that moment in time.
Which is what makes the question kind of unknowable. Because we can't rerun our lives to see if we could make different decisions with all of the exact same conditions as before. Even running the choice twice isn't the same. Because the second time you do it, you're now a person who has previously made this choice. And that makes the scenario different, because you are different. We have no real way of testing free will.
But better still: the question does not matter at all.
Either free will exists or it doesn't. There's no spectrum of "50% will" or whatever. You can either make choices or you're essentially the result of all the forces acting upon you.
So, what are the consequences of both scenarios?
If free will exists, then fine, we can make choices. We can choose to do whatever. There's nothing really interesting to be said about this branch.
However. If free will does not exist, then there's something weird going on. Because if free will does not exist, I don't have any choice in whether or not to post this message. I post this message because your post elicits that response in me. Just like you made your post for the same reason. And we just keep pulling this thread all the way back to the big bang.
But we also don't have the choice in how we feel about this discussion either. You will either accept this or not based on the various physical, biological, and chemical processes going on inside of and around you. So you will either agree or disagree and that decision itself is preordained. Regardless if it is true or not. You're either the type to believe in free will or not and you can't choose that. Because if you could choose that, you'd have free will.
Even if you believe you are making a change, you're not. Because you were going to make that change due to the forces at work on you. Forces that were eventually going to interact with you because those forces themselves are the products of other forces, etc. So if you hear all this, take it to heart, and decide to live a life of apathy because you have no free will and nothing matters. Then that's what was going to happen at this point and time regardless.