Hi@MD,
The following copy-snapshot command copies the specified unencrypted snapshot from the us-west-2 Region to the current Region and encrypts the new snapshot using the specified AWS KMS customer master key (CMK).
aws ec2 copy-snapshot \
    --source-region us-west-2 \
    --source-snapshot-id snap-066877671789bd71b \
    --encrypted \
    --kmd-key-id alias/my-cmk