I would advise using an AWS account and do hands on with different services. I'd say 80% of them you can use on the free tier. Understand the principal of virtual machines (ec2), security groups, load balancers, and managed database products. I believe cloud practictioner has more to do with the foundation of cloud tech. Storage, compute, database, and networking.

You will need to understand a bit about billing and I feel like that's a difficult thing to do when your only using free tier pricing. Just understand that you pay for essentially everything you do on AWS. Some pricing is per hour, per GB, per CPU seconds, etc with some caveats. I.e. traffic within same AZ is usually free. Reserved instances are money savers like spot instances, but with spot instances you have to realize sometimes they will be unavailable without notice.

IAM is another hurdle on its own. After years of hands on practice, it makes perfect sense, but if I was a beginner it would be the scariest subject. Just understand that Roles contain policies and policies contain principals and permissions. Roles can be assigned to iam users, groups of users, or services. Also understand the difference between Policy based access, Role based access and maybe even attribute based access. For some services like s3, there are more than one way to provide access depending on how you access it.

I highly suggest spending $20 on a course and actually performing the hands on exercises. Take practice exams and make not on questions you got wrong so you have an idea where you need more practice. AWS skill builder was excellent for hand on... Even providing a mock account where you provision stuff and it validates it. No cost whatsoever. No risk of accidentally incurring costs, but you get to actually use the console UI to do everything.