First Round will be Assigment of creating React App and put it on git repo and then second round will be extension of assigment in live interview where they can ask to add some Functinality to your code

Mostly the interview is going on the react concepts and indepth questions related to the react and sometimes asks to develop functionality on react project which they will assign to you. If you are good at building projects in react it will be very easy to place in a react developer role.