Coming to a conclusion that makes sense to you and you are accepting of is how inner peace is achieved, so yes, this is one way that it can be realized. If you acknowledge there are certain things you simply cannot know then you won't stress throughout your life trying to figure them out.
A person will never accurately predict their own future. Every time they do, they are setting themselves up for failure and depression. Sure, a person can do things to get the outcomes they want, but it takes a lot of hard work and determination to get there. Plus, there will always be setbacks along the way.
Inner peace looks different to everyone and as such not everyone will attain it. I don't know if that means you necessarily have to accept your fate ... Some people are perfectly at home with adversity, playing the long game, or living for something bigger than themselves. They don't necessarily win or submit, they can just find happiness in what they've accomplished and be done with it.
I think inner peace may be achieved by accepting fate, but only if that is what you believe. I personally don't believe our fate is planned, but unknown. For me it would be to accept that we don't know what is going to happen to us, no one does, and that we should be happy for what we have now. I also think we need to learn that since we are all different that we need to stop putting pressure and expectations on others to do what we would do. For example. I read a book that was talking about how we all can see the same situation, but see different things. Like a cluttered house to me might be a perfect arrangement of memories to another. So the person with all the clutter is actually their way of being at peace where it would be a distraction to me. So with that being said how can we think that inner peace can be achieved the same way for everyone?
Inner peace is realized only when the person finds themselves at peace with the rest of the world. There is no set formula for how this takes place, or when it does in someone's life. Each person must take a different journey through life, and there is no recipe to peace.