This is such an interesting topic. I think it’s one of the reasons Astrophysics can be so humbling.
In reality it is a philosophical question. I think if you believe you have free will, then that is enough. What would you do if you didn’t have it? That very thought would be destined. How would you challenge it? Hold your breath until you pass out… not possible… do you not have free will? I am in favor of ‘I think; therefore I am’
Now I would tend to approach this more from a quantum mechanics perspective. There is much randomness at a micro level that is built into the ultimate macro universe. I choose to think free will starts here, and for me it’s quite elegant because it allows for probability and predictability without absolute certainty. Again, this a belief I choose, no proof here.
As others have mentioned there are a few authors who explore this at a high enough level to grasp without years of study.
The grand design by Steven Hawking jumps to mind and it a great starting point. Much has happened since 2010 in our understanding of the cosmos.