CloudFront pricing for CloudWatch matrix

Hello.

CloudWatch metrics that are displayed by default in CloudFront are free to use.
https://docs.aws.amazon.com/AmazonCloudFront/latest/DeveloperGuide/monitoring-using-cloudwatch.html

Amazon CloudFront is integrated with Amazon CloudWatch and automatically publishes operational metrics for distributions and edge functions (both Lambda@Edge and CloudFront Functions). Many of these metrics are displayed in a set of graphs in the CloudFront console, and are also accessible by using the CloudFront API or CLI. All of these metrics are available in the CloudWatch console or through the CloudWatch API or CLI. The CloudFront metrics don't count against CloudWatch quotas (formerly known as limits) and don't incur any additional cost.

However, please note that if you enable additional metrics, they will not be included in the free tier.
https://docs.aws.amazon.com/AmazonCloudFront/latest/DeveloperGuide/viewing-cloudfront-metrics.html#monitoring-console.distributions-additional