Using the query parameter to filter the output.
Quering using the JMESPath syntax to create expressions to filter out your output.
filter by tag using query
aws rds describe-db-instances --query "DBInstances[0].[DBInstanceIdentifier,TagList[?Key=='Name'].Value]"
rds with their name tag
aws rds describe-db-instances --query "DBInstances[].[DBInstanceIdentifier,TagList[?Key=='Name'].Value]" --output text | awk 'NR%2{printf $0" ";next;}1'References link