I am an eager learner of the violin for a few days and a fan of classical music for a long time. It's not possible for me to hire a tutor to give me lessons. I'm trying to learn online. Currently, I am following Franco-Belgian bow grip. But, I am a big fan of Hilary Hahn and her bow grip is hybrid and hand position is different. I tried to study her grip style but I find it difficult to get the full gist of it from different snapshots. Can I unlearn and change a style 1 year later? Would this be too difficult?
For the first couple of months of learning to play the violin your bow hold will change and evolve as you gain in skill and strength in the small muscles involved. After a year you can still change your bow hold style but it will involve a lot more work.
Note that even when you have a settled bow hold it is not set in stone. When you play in different parts of the bow or you use different bow strokes the shape of your right hand will change to help you do what you are trying to do.
If at all possible you would do well to get a teacher who can show you and guide you into holding the bow and much else besides. It really will speed your development and help you avoid bad habits that can take time to eliminate later. That said in the current Covid-19 situation that is not easy and in many places isn't possible.
Hilary Hahn, by the way, has a classical Franco-Belgian bow hold. Today this is the standard bow hold which is taught by most teachers and used by most violinists. It has become so standard that often it is taught without a name as just the way to hold a bow. Here is a YouTube video giving a quick demonstration.
It wasn't always so. Two of the greats of the 20th century, Jascha Heifetz and Nathan Millstein, used the Russian bow hold. Here is another, much longer (if you are unorthodox you have to spend longer justifying yourself :-), YouTube video by a modern gypsy-jazz violinist who uses the Russian bow hold.