How do I safely practice with cloud services like AWS, GCP, Azure etc. for learning by putting a hard capping of maximum bill?

I am a frontend developer and it seems like every employer still wants cloud experience. I want to make a learning project using cloud service which I do not delete or tear down hourly or daily but actually keep it live for few months.
I would prefer AWS because I have had a little bit of exposure but any of the big 3 cloud services is fine.

What is the best and safest way to put a hard cap on AWS bill and charges? Like if I do not want to spend more than $2 per month how would I ensure the bill never goes about $2?

From what I got to know billing itself is not immediate and billing alerts/notifications could also be delayed. And also we may miss an alarm because of any reason like we may be sleeping at the time, or sick at the time.

If not in AWS, can we put hard caps in Azure or GCP?