If you already know algorithms and data structures, use leetcode. Solve most Google tagged questions. You can also use pramp for mock interviews.

Thanks a lot for the insight and suggestion. Is there any online resource to follow for the System and Low level design question asked in Goolgle?

Leetcode is basically the gold standard.

Thank you. Any suggestion for the System and Low level design rounds?

When I went through this about 3 years ago, the approach for System Design was to read the Data Intensive Application Development book, go through the Grokking System Design course, read all the summary materials I could find, watch a bunch of YouTube videos on specific examples and deep dive into areas I felt weak at. Took notes throughout and refreshed myself before every interview.

Didn't prep for any low level stuff.

interviewing.io watch some of their videos on github

Thanks you so much!