Check out example codes for "how to make s3 bucet objects publicj". It will help you in understanding the concepts better.

Code Example 1

{"Version": "2008-10-17",
"Statement": [{"Sid": "AllowPublicRead",
"Effect": "Allow",
"Principal": {
"AWS": "*"
},
"Action": "s3:GetObject",
"Resource": "arn:aws:s3:::YOUR-BUCKET-NAME/*"
}]}

Learn ReactJs, React Native from akashmittal.com