Yes ... no ... maybe.
The thing is the most extreme versions of determinism and free will are probably the clockwork universe and the creator god who has full power over his mind to create an entire universe for and by themselves.
But let's, for the sake of argument, discard the creator god, due to a lack of manifestations to talk about, and move from the "game developer" to the "gamer". That is imagine yourself playing a computer game. Then an avatar, a representation or manifestation of yourself would be serving as your body which would be part of the game world, a world that is NOT of your own creation and that follows certain rules and limits the abilities of your avatar. At the same time your mind would not be part of that game world. You can interact with it and you can be moved emotionally by it but the interaction happens through an interface and there is no deterministic 1:1 relation between the game world and the real world mind.
So in other words despite the fact that the game might be highly deterministic, maybe even predeterministic in parts (cut scenes) or as a whole (predetermined story line or paths), that there is a god in this universe (game developer) and that they gave life in this universe a purpose (called it a racer, shooter, rpg, etc) and even punishes you if you fail to adhere to it (taking damage, "game over!", etc), you might still choose not to follow that purpose and instead give life it's own purpose. Such as finding crashes and explosions in a racing game much more fun than actually winning a race, strolling around in an park rather than going on an epic quest, trying to get away with crime and breaking the game rather than playing by it's rules and so on.
You'd have a mind-body-... not just dualism but even a distinction between the two, your avatar would be in possession of a soul which distinguishes it from NPCs (non-player-characters) who would be more like philosophical zombies or even less autonomous.
Whether you place that "mind" in your brain, your guts, your heart, your stomach or your lower abdomen, it would be in possession of a "free will", one that is not determined by it's environment and that can want what it wants by it's own volition only limited by it's own imagination.
And to a large extend that is the intuition that probably most people feel about themselves and what they conversely see in other people. And what to a large extend has also found it's way into our ethical considerations. The idea that "if I were to swap minds with this other person and take on their body would I have acted the same or would there have been other options".
Because while the "game world", or "the world" for the sake of arguments, can include situations where the circumstances determine the outcome regardless of the actions or volition of the individual, these are largely considered edge cases, same for instinctive decisions vs those that are the result of long and methodic thought which are seen as more of an expression of the self, the mind, then the body. For example an ad hoc homicide in a fit of rage is usually seen as less evil than a homicide with intend and without factors such as self-defense or defense of others.
That all being said in favor of free will, we still could not find any trace of a soul, yet at the same time we have found extensive connections between the body and the brain where we most strongly expected the mind to be...
On the other hand we also developed quite a fondness for deterministic systems because they make the complex nature of the universe appear to be more ... idk digestible? Like if things happen according to deterministic patterns then we could find these pattern and use them to predict what comes next, which greatly increases our abilities to fulfill our needs. And we've been quite successful with that so much so that some argue it might be more than a hypothesis but that the world might in fact be deterministic.
This likely fails to be predetermination due to the fact that there are things in the universe that are likely random (at least from what we know now) and as such the future can't be predicted explicitly but only stochastically. But even in that case actual "free will" would kinda be a problem for that kind of thinking because a truly free will could render our hopes of finding the patterns of the universe to be futile due to the fact that there are still beings, including ourselves, which would pertube the universe ever so slightly or even massively that there is a hard limit to how much we can know about the universe before having to insert human shaped "chaos fields" into our theories.
Also even if the interface between the self or mind and the world isn't 1:1 deterministic it nonetheless works in both directions and the imaginative power of the self is tied to it's impressions and perceptions of the world so the circumstances do shape the mind even if it's less of a careful sculpturing process and more of a big mess which constantly adds subtracts and connects parts.
And that way of thinking also found it's way into our systems of ethics, the idea of observing patterns, of cause and effect relations etc. Even the creator god and the concept of being able to not just find law, but make law and create desired behavior has made it into our legal and ethical considerations.
So if you find no practical difference between a legal system in a deterministic world view and in a free will world view, then that is likely caused by the fact that it already is a compromise between the two having drawn from both of these traditions. So even the concept of the existence or inexistence of free will likely already had a major influence on that debate.
Now there are 2 more things to consider, name "And what is it?" and "Does it matter if we knew?".
And with regards to "And what is it", you probably end up with a similar agnosticism as with regards to whether god exists. In the sense of "we don't know, as of right now can't know and as long as it doesn't manifests in ways that lets us know what it is, it also doesn't really matter". The thing is if it is deterministic and we're just gears in a clockwork, then we had no chance but to ask these questions anyway or even if there was a chance, that's where we are. And if we have free will, then we have free will, whether we want to or not.
That being said it still matters a whole lot whether we know about it or not. Like it could change everything, it might show that a universal morality is in fact real and an emerging phenomenon, it might show that it is complete nonsense and that rather than good and evil there is only a personal good or bad with regards to aligning with the self-interest or not, or it could be both. There could be more empathy or less, there could be more appreciation of the value of the individual or none at all. Rehabilitation could be improved or discarded in favor or "repair" (idk just remove the bad ideas and insert good ones). It could foster a hive mind or an zombification, a fully physical mind could mean eternal life as data, so it could radically alter our conception of life and death and as such what is considered harmful or not. It could give life purpose or remove it altogether.
And with regards to ethics, what if you believe one, act accordingly and it happens to be the other? Because that is inevitably what we end up doing even to some extend. Is that futile, stupid, harmful, rational, ...?
So in other words the consequence of that could be quite profound but as long as we don't know what it is and can't figure it out it doesn't really matter either way.