Here’s how to enable performance insights on a RDS instance.

Enable

aws rds modify-db-instance \
--db-instance-identifier sample-db-instance \
--enable-performance-insights \
--region us-east-1 \
--profile default

Disable

aws rds modify-db-instance \
--db-instance-identifier sample-db-instance \
--no-enable-performance-insights \
--region us-east-1 \
--profile default