Cloud environment had exponential growth over the course (AWS didn't have RDS when I started) and I wanted to get a firm graps on the subject before venturing into new job. During covid-19 pandemic, I have racked up 4 professional cloud certificates(2 AWS, 2 GCP). I am proud of my achievement. Being certified is rewarding experience, but the knowledge and exprience I gained was more rewarding. If you are interested preparing and taking the test will be great first step, if you are already experienced, this will harden your knowledge in every aspect.
If you do not know where to start, I recommend you to start with coursera. You can get first week free and google provides 50% off on first month. (refer to last section for the link)
Cloud Engineering with Google Cloud
Cloud Architecture with Google Cloud
Data Engineering with Google Cloud
Getting hands on is essential you make your knowledge tangible by actually working on the product. Google offers 30 day free subscriptions. I think the quest badge they offer is great example of gamification done right way. Learnig through qwiklab was really fun process for me. You can synthesize your knowledge as you get hands on with what you have learned through texts and slides.
Jinwook B. | Qwiklabs
If you don't have much time you should at least go through following quests.
For Cloud Architect
Cloud Architecture: Design, Implement, and Manage | Qwiklabs
For Data Engineering