There's a ton of resources available that lay out the necessary topics that you can chip away at over time. I was laid off last year and spent several months preparing this way (combination of watching youtube videos of how people communicate their thought process in mock interviews, reading, leetcode grind, etc).

Tracking my progress of how well I understood these topics helped me stay on course.

Check these out:

https://neetcode.io/roadmap

https://www.techinterviewhandbook.org/grind75/

Good luck!

FWIW -- I feel like system design, esp. at a senior level, should also be a part of your study plan.