How to check whether s3 access key has access to a specific bucket or not in aws using boto3
If you are copying objects between Amazon S3 buckets that belong to different AWS accounts, then you will need to use a single set of credentials that have:

GetObject permission on the source bucket
PutObject permission on the destination bucket

Also, the CopyObject command should be sent to the destination bucket to avoid problems with object ownership.
Therefore, I would recommend:

Use credentials from the destination account (dest-IAM-user)
Add a bucket policy to the source bucket that permits GetObject access by dest-IAM-user
I am trying to copy files from 2 different bucket which are in two different aws account using same access key.
So it provide an error saying 403 forbidden.So what i want to do is, I want to check whether the access key that i am using to copy the file has permission to those bucket before i copy the file using boto3. Is there are anyway to do this?