IAM: CLI: How to get contents of a policy?

A. Policy: AmazonS3ReadOnlyAccess
B. Arn: arn:aws:iam::aws:policy/AmazonS3ReadOnlyAccess

C. Console view:
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": [
"s3:Get*",
"s3:List*"
],
"Resource": "*"
}
]
}

D. How can I get that JSON (C.) output from CLI?

Please, advise. Thank you.

~ Mike