Can I change the vat/tax of my product based on category , because I only want to change the vat/tax of specific products.
It depends on where you are located,
For North American shops there is this guide, navigate to Overriding taxes for a group of items for detailed steps. There you can create overrides for categories.
If you are in the EU it can not be done automatically based on category. You will need to create a new manual tax rate and assign it to the products.
Hope this helps, let me know if you need more info!