These are two separate topics. You acquire domain knowledge, when you actually work in that domain or from school. Having a good background in industry domain is great but not essential for Automation Engineer. Sad to say, i cannot provide you background on the domains. How depth domain knowledge you need is really based on the projects. Some projects will need more and some won't need any. I will suggest focus more on automation ( coding side ) and implement some pilot projects. Also, google some projects people did on different domains and just think how you can implement your automation over it. There are many many examples in google. This will help you to more in interview. Good luck